为什么strcpy'；d在C中_C_File_Character Encoding

为什么strcpy'；d在C中

c file character-encoding

为什么strcpy'；d在C中,c,file,character-encoding,C,File,Character Encoding,源代码： char CUSTOMERS_FILE[50] = "customers.txt"; typedef struct Customer { char name[50]; char password[50]; char billing_address[100]; char phone_number[15]; double amount_paid; double amount_due; char date[20]; } Custome

源代码：

char CUSTOMERS_FILE[50] = "customers.txt";

typedef struct Customer {
    char name[50];
    char password[50];
    char billing_address[100];
    char phone_number[15];
    double amount_paid;
    double amount_due;
    char date[20];
} Customer;

char* read_string(int length) {
    char data[length];
    rewind(stdin);
    fgets(data, length, stdin);

    if (data[0] == '\n') {
        data[0] = '\0';
    }

    strtok(data, "\n");

    printf("DATA: %s", data);

    return data;
}

void handle_modify_customer(Customer customer) {
    Customer edited_details;

    printf("\nMODIFYING DETAILS\n==============\n\n");

    printf("CREATE A CUSTOMER PROFILE\n=========================\n");

    printf("Name (%s): ", customer.name);
    strcpy(edited_details.name, read_string(50));

    printf("Password (%s): ", customer.password);
    strcpy(edited_details.password, read_string(50));

    printf("Billing Address (%s): ", customer.billing_address);
    strcpy(edited_details.billing_address, read_string(100));

    printf("Phone Number (%s): ", customer.phone_number);
    strcpy(edited_details.phone_number, read_string(15));

    printf("Amount Paid (%10.2lf): ", customer.amount_paid);
    scanf("%lf", &edited_details.amount_paid);

    printf("Amount Due (%10.2lf): ", customer.amount_due);
    scanf("%lf", &edited_details.amount_due);

    printf("Payment Date (%s): ", customer.date);
    strcpy(edited_details.date, read_string(20));

    /*
    if (strlen(edited_details.name) == '\0' || strlen(edited_details.billing_address) == '\0' || strlen(edited_details.password) == '\0' || strlen(edited_details.phone_number) == '\0' || strlen(edited_details.date) == '\0') {
        printf("All fields must be filled in!");
        handle_modify_customer(customer);
    }*/

    if (edited_details.name[0] == '\0' || edited_details.billing_address[0] == '\0' || edited_details.password[0] == '\0' || edited_details.phone_number[0] == '\0' || edited_details.date[0] == '\0') {
        printf("All fields must be filled in!");
        handle_modify_customer(customer);
    }

    FILE *file = fopen(CUSTOMERS_FILE, "r");
    FILE *new_file = fopen("customers_new.txt", "ab+");

    Customer record;

    while (fscanf(file, "[%[^]]], [%[^]]], [%[^]]], [%[^]]], [%lf], [%lf], [%[^]]]\n",
                  record.name, record.password, record.billing_address, record.phone_number,
                  &record.amount_paid, &record.amount_due, record.date) == 7)
    {
        if (strcmp(customer.name, record.name) == 0) {
            printf("P: %s\nD: %s", edited_details.phone_number, edited_details.date);
            fprintf(new_file, "[%s], [%s], [%s], [%s], [%lf], [%lf], [%s]\n", edited_details.name, edited_details.password, edited_details.billing_address, edited_details.phone_number, edited_details.amount_paid, edited_details.amount_due, edited_details.date);
        } else {
            fprintf(new_file, "[%s], [%s], [%s], [%s], [%lf], [%lf], [%s]\n", record.name, record.password, record.billing_address, record.phone_number, record.amount_paid, record.amount_due, record.date);
        }
    }

    fclose(file);
    fclose(new_file);

    remove(CUSTOMERS_FILE);
    rename("customers_new.txt", CUSTOMERS_FILE);

    printf("\nThe customer details have been successfully modified!\n");
    key_to_continue();
}

MODIFYING DETAILS
==============

CREATE A CUSTOMER PROFILE
=========================
Name (dumbfk): test
DATA: testPassword (abc123): lol
DATA: lolBilling Address (pukima jalan): lol
DATA: lolPhone Number (6969696969): 499449
DATA: 499449Amount Paid (   6969.00): 499449
Amount Due (6969699.00): 499494
Payment Date (6/9/1969): 22/2/2000
DATA: 22/2/2000P: �O���
D: �O���
The customer details have been successfully modified!

[well lol], [abc123], [wtf bro? 24], [0183188383], [3000.000000], [4000.000000], [12/12/2012]
[chow hai], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[lol head], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[stupid face], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[dumbfk], [abc123], [pukima jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]

[well lol], [abc123], [wtf bro? 24], [0183188383], [3000.000000], [4000.000000], [12/12/2012]
[chow hai], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[lol head], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[stupid face], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[test], [lol], [lol], [�O���], [499449.000000], [499494.000000], [�O���]

执行示例：

char CUSTOMERS_FILE[50] = "customers.txt";

typedef struct Customer {
    char name[50];
    char password[50];
    char billing_address[100];
    char phone_number[15];
    double amount_paid;
    double amount_due;
    char date[20];
} Customer;

char* read_string(int length) {
    char data[length];
    rewind(stdin);
    fgets(data, length, stdin);

    if (data[0] == '\n') {
        data[0] = '\0';
    }

    strtok(data, "\n");

    printf("DATA: %s", data);

    return data;
}

void handle_modify_customer(Customer customer) {
    Customer edited_details;

    printf("\nMODIFYING DETAILS\n==============\n\n");

    printf("CREATE A CUSTOMER PROFILE\n=========================\n");

    printf("Name (%s): ", customer.name);
    strcpy(edited_details.name, read_string(50));

    printf("Password (%s): ", customer.password);
    strcpy(edited_details.password, read_string(50));

    printf("Billing Address (%s): ", customer.billing_address);
    strcpy(edited_details.billing_address, read_string(100));

    printf("Phone Number (%s): ", customer.phone_number);
    strcpy(edited_details.phone_number, read_string(15));

    printf("Amount Paid (%10.2lf): ", customer.amount_paid);
    scanf("%lf", &edited_details.amount_paid);

    printf("Amount Due (%10.2lf): ", customer.amount_due);
    scanf("%lf", &edited_details.amount_due);

    printf("Payment Date (%s): ", customer.date);
    strcpy(edited_details.date, read_string(20));

    /*
    if (strlen(edited_details.name) == '\0' || strlen(edited_details.billing_address) == '\0' || strlen(edited_details.password) == '\0' || strlen(edited_details.phone_number) == '\0' || strlen(edited_details.date) == '\0') {
        printf("All fields must be filled in!");
        handle_modify_customer(customer);
    }*/

    if (edited_details.name[0] == '\0' || edited_details.billing_address[0] == '\0' || edited_details.password[0] == '\0' || edited_details.phone_number[0] == '\0' || edited_details.date[0] == '\0') {
        printf("All fields must be filled in!");
        handle_modify_customer(customer);
    }

    FILE *file = fopen(CUSTOMERS_FILE, "r");
    FILE *new_file = fopen("customers_new.txt", "ab+");

    Customer record;

    while (fscanf(file, "[%[^]]], [%[^]]], [%[^]]], [%[^]]], [%lf], [%lf], [%[^]]]\n",
                  record.name, record.password, record.billing_address, record.phone_number,
                  &record.amount_paid, &record.amount_due, record.date) == 7)
    {
        if (strcmp(customer.name, record.name) == 0) {
            printf("P: %s\nD: %s", edited_details.phone_number, edited_details.date);
            fprintf(new_file, "[%s], [%s], [%s], [%s], [%lf], [%lf], [%s]\n", edited_details.name, edited_details.password, edited_details.billing_address, edited_details.phone_number, edited_details.amount_paid, edited_details.amount_due, edited_details.date);
        } else {
            fprintf(new_file, "[%s], [%s], [%s], [%s], [%lf], [%lf], [%s]\n", record.name, record.password, record.billing_address, record.phone_number, record.amount_paid, record.amount_due, record.date);
        }
    }

    fclose(file);
    fclose(new_file);

    remove(CUSTOMERS_FILE);
    rename("customers_new.txt", CUSTOMERS_FILE);

    printf("\nThe customer details have been successfully modified!\n");
    key_to_continue();
}

MODIFYING DETAILS
==============

CREATE A CUSTOMER PROFILE
=========================
Name (dumbfk): test
DATA: testPassword (abc123): lol
DATA: lolBilling Address (pukima jalan): lol
DATA: lolPhone Number (6969696969): 499449
DATA: 499449Amount Paid (   6969.00): 499449
Amount Due (6969699.00): 499494
Payment Date (6/9/1969): 22/2/2000
DATA: 22/2/2000P: �O���
D: �O���
The customer details have been successfully modified!

[well lol], [abc123], [wtf bro? 24], [0183188383], [3000.000000], [4000.000000], [12/12/2012]
[chow hai], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[lol head], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[stupid face], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[dumbfk], [abc123], [pukima jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]

[well lol], [abc123], [wtf bro? 24], [0183188383], [3000.000000], [4000.000000], [12/12/2012]
[chow hai], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[lol head], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[stupid face], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[test], [lol], [lol], [�O���], [499449.000000], [499494.000000], [�O���]

数据文件（之前）：

char CUSTOMERS_FILE[50] = "customers.txt";

typedef struct Customer {
    char name[50];
    char password[50];
    char billing_address[100];
    char phone_number[15];
    double amount_paid;
    double amount_due;
    char date[20];
} Customer;

char* read_string(int length) {
    char data[length];
    rewind(stdin);
    fgets(data, length, stdin);

    if (data[0] == '\n') {
        data[0] = '\0';
    }

    strtok(data, "\n");

    printf("DATA: %s", data);

    return data;
}

void handle_modify_customer(Customer customer) {
    Customer edited_details;

    printf("\nMODIFYING DETAILS\n==============\n\n");

    printf("CREATE A CUSTOMER PROFILE\n=========================\n");

    printf("Name (%s): ", customer.name);
    strcpy(edited_details.name, read_string(50));

    printf("Password (%s): ", customer.password);
    strcpy(edited_details.password, read_string(50));

    printf("Billing Address (%s): ", customer.billing_address);
    strcpy(edited_details.billing_address, read_string(100));

    printf("Phone Number (%s): ", customer.phone_number);
    strcpy(edited_details.phone_number, read_string(15));

    printf("Amount Paid (%10.2lf): ", customer.amount_paid);
    scanf("%lf", &edited_details.amount_paid);

    printf("Amount Due (%10.2lf): ", customer.amount_due);
    scanf("%lf", &edited_details.amount_due);

    printf("Payment Date (%s): ", customer.date);
    strcpy(edited_details.date, read_string(20));

    /*
    if (strlen(edited_details.name) == '\0' || strlen(edited_details.billing_address) == '\0' || strlen(edited_details.password) == '\0' || strlen(edited_details.phone_number) == '\0' || strlen(edited_details.date) == '\0') {
        printf("All fields must be filled in!");
        handle_modify_customer(customer);
    }*/

    if (edited_details.name[0] == '\0' || edited_details.billing_address[0] == '\0' || edited_details.password[0] == '\0' || edited_details.phone_number[0] == '\0' || edited_details.date[0] == '\0') {
        printf("All fields must be filled in!");
        handle_modify_customer(customer);
    }

    FILE *file = fopen(CUSTOMERS_FILE, "r");
    FILE *new_file = fopen("customers_new.txt", "ab+");

    Customer record;

    while (fscanf(file, "[%[^]]], [%[^]]], [%[^]]], [%[^]]], [%lf], [%lf], [%[^]]]\n",
                  record.name, record.password, record.billing_address, record.phone_number,
                  &record.amount_paid, &record.amount_due, record.date) == 7)
    {
        if (strcmp(customer.name, record.name) == 0) {
            printf("P: %s\nD: %s", edited_details.phone_number, edited_details.date);
            fprintf(new_file, "[%s], [%s], [%s], [%s], [%lf], [%lf], [%s]\n", edited_details.name, edited_details.password, edited_details.billing_address, edited_details.phone_number, edited_details.amount_paid, edited_details.amount_due, edited_details.date);
        } else {
            fprintf(new_file, "[%s], [%s], [%s], [%s], [%lf], [%lf], [%s]\n", record.name, record.password, record.billing_address, record.phone_number, record.amount_paid, record.amount_due, record.date);
        }
    }

    fclose(file);
    fclose(new_file);

    remove(CUSTOMERS_FILE);
    rename("customers_new.txt", CUSTOMERS_FILE);

    printf("\nThe customer details have been successfully modified!\n");
    key_to_continue();
}

MODIFYING DETAILS
==============

CREATE A CUSTOMER PROFILE
=========================
Name (dumbfk): test
DATA: testPassword (abc123): lol
DATA: lolBilling Address (pukima jalan): lol
DATA: lolPhone Number (6969696969): 499449
DATA: 499449Amount Paid (   6969.00): 499449
Amount Due (6969699.00): 499494
Payment Date (6/9/1969): 22/2/2000
DATA: 22/2/2000P: �O���
D: �O���
The customer details have been successfully modified!

[well lol], [abc123], [wtf bro? 24], [0183188383], [3000.000000], [4000.000000], [12/12/2012]
[chow hai], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[lol head], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[stupid face], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[dumbfk], [abc123], [pukima jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]

[well lol], [abc123], [wtf bro? 24], [0183188383], [3000.000000], [4000.000000], [12/12/2012]
[chow hai], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[lol head], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[stupid face], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[test], [lol], [lol], [�O���], [499449.000000], [499494.000000], [�O���]

数据文件（之后）：

char CUSTOMERS_FILE[50] = "customers.txt";

typedef struct Customer {
    char name[50];
    char password[50];
    char billing_address[100];
    char phone_number[15];
    double amount_paid;
    double amount_due;
    char date[20];
} Customer;

char* read_string(int length) {
    char data[length];
    rewind(stdin);
    fgets(data, length, stdin);

    if (data[0] == '\n') {
        data[0] = '\0';
    }

    strtok(data, "\n");

    printf("DATA: %s", data);

    return data;
}

void handle_modify_customer(Customer customer) {
    Customer edited_details;

    printf("\nMODIFYING DETAILS\n==============\n\n");

    printf("CREATE A CUSTOMER PROFILE\n=========================\n");

    printf("Name (%s): ", customer.name);
    strcpy(edited_details.name, read_string(50));

    printf("Password (%s): ", customer.password);
    strcpy(edited_details.password, read_string(50));

    printf("Billing Address (%s): ", customer.billing_address);
    strcpy(edited_details.billing_address, read_string(100));

    printf("Phone Number (%s): ", customer.phone_number);
    strcpy(edited_details.phone_number, read_string(15));

    printf("Amount Paid (%10.2lf): ", customer.amount_paid);
    scanf("%lf", &edited_details.amount_paid);

    printf("Amount Due (%10.2lf): ", customer.amount_due);
    scanf("%lf", &edited_details.amount_due);

    printf("Payment Date (%s): ", customer.date);
    strcpy(edited_details.date, read_string(20));

    /*
    if (strlen(edited_details.name) == '\0' || strlen(edited_details.billing_address) == '\0' || strlen(edited_details.password) == '\0' || strlen(edited_details.phone_number) == '\0' || strlen(edited_details.date) == '\0') {
        printf("All fields must be filled in!");
        handle_modify_customer(customer);
    }*/

    if (edited_details.name[0] == '\0' || edited_details.billing_address[0] == '\0' || edited_details.password[0] == '\0' || edited_details.phone_number[0] == '\0' || edited_details.date[0] == '\0') {
        printf("All fields must be filled in!");
        handle_modify_customer(customer);
    }

    FILE *file = fopen(CUSTOMERS_FILE, "r");
    FILE *new_file = fopen("customers_new.txt", "ab+");

    Customer record;

    while (fscanf(file, "[%[^]]], [%[^]]], [%[^]]], [%[^]]], [%lf], [%lf], [%[^]]]\n",
                  record.name, record.password, record.billing_address, record.phone_number,
                  &record.amount_paid, &record.amount_due, record.date) == 7)
    {
        if (strcmp(customer.name, record.name) == 0) {
            printf("P: %s\nD: %s", edited_details.phone_number, edited_details.date);
            fprintf(new_file, "[%s], [%s], [%s], [%s], [%lf], [%lf], [%s]\n", edited_details.name, edited_details.password, edited_details.billing_address, edited_details.phone_number, edited_details.amount_paid, edited_details.amount_due, edited_details.date);
        } else {
            fprintf(new_file, "[%s], [%s], [%s], [%s], [%lf], [%lf], [%s]\n", record.name, record.password, record.billing_address, record.phone_number, record.amount_paid, record.amount_due, record.date);
        }
    }

    fclose(file);
    fclose(new_file);

    remove(CUSTOMERS_FILE);
    rename("customers_new.txt", CUSTOMERS_FILE);

    printf("\nThe customer details have been successfully modified!\n");
    key_to_continue();
}

MODIFYING DETAILS
==============

CREATE A CUSTOMER PROFILE
=========================
Name (dumbfk): test
DATA: testPassword (abc123): lol
DATA: lolBilling Address (pukima jalan): lol
DATA: lolPhone Number (6969696969): 499449
DATA: 499449Amount Paid (   6969.00): 499449
Amount Due (6969699.00): 499494
Payment Date (6/9/1969): 22/2/2000
DATA: 22/2/2000P: �O���
D: �O���
The customer details have been successfully modified!

[well lol], [abc123], [wtf bro? 24], [0183188383], [3000.000000], [4000.000000], [12/12/2012]
[chow hai], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[lol head], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[stupid face], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[dumbfk], [abc123], [pukima jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]

[well lol], [abc123], [wtf bro? 24], [0183188383], [3000.000000], [4000.000000], [12/12/2012]
[chow hai], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[lol head], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[stupid face], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[test], [lol], [lol], [�O���], [499449.000000], [499494.000000], [�O���]

问题：

char CUSTOMERS_FILE[50] = "customers.txt";

typedef struct Customer {
    char name[50];
    char password[50];
    char billing_address[100];
    char phone_number[15];
    double amount_paid;
    double amount_due;
    char date[20];
} Customer;

char* read_string(int length) {
    char data[length];
    rewind(stdin);
    fgets(data, length, stdin);

    if (data[0] == '\n') {
        data[0] = '\0';
    }

    strtok(data, "\n");

    printf("DATA: %s", data);

    return data;
}

void handle_modify_customer(Customer customer) {
    Customer edited_details;

    printf("\nMODIFYING DETAILS\n==============\n\n");

    printf("CREATE A CUSTOMER PROFILE\n=========================\n");

    printf("Name (%s): ", customer.name);
    strcpy(edited_details.name, read_string(50));

    printf("Password (%s): ", customer.password);
    strcpy(edited_details.password, read_string(50));

    printf("Billing Address (%s): ", customer.billing_address);
    strcpy(edited_details.billing_address, read_string(100));

    printf("Phone Number (%s): ", customer.phone_number);
    strcpy(edited_details.phone_number, read_string(15));

    printf("Amount Paid (%10.2lf): ", customer.amount_paid);
    scanf("%lf", &edited_details.amount_paid);

    printf("Amount Due (%10.2lf): ", customer.amount_due);
    scanf("%lf", &edited_details.amount_due);

    printf("Payment Date (%s): ", customer.date);
    strcpy(edited_details.date, read_string(20));

    /*
    if (strlen(edited_details.name) == '\0' || strlen(edited_details.billing_address) == '\0' || strlen(edited_details.password) == '\0' || strlen(edited_details.phone_number) == '\0' || strlen(edited_details.date) == '\0') {
        printf("All fields must be filled in!");
        handle_modify_customer(customer);
    }*/

    if (edited_details.name[0] == '\0' || edited_details.billing_address[0] == '\0' || edited_details.password[0] == '\0' || edited_details.phone_number[0] == '\0' || edited_details.date[0] == '\0') {
        printf("All fields must be filled in!");
        handle_modify_customer(customer);
    }

    FILE *file = fopen(CUSTOMERS_FILE, "r");
    FILE *new_file = fopen("customers_new.txt", "ab+");

    Customer record;

    while (fscanf(file, "[%[^]]], [%[^]]], [%[^]]], [%[^]]], [%lf], [%lf], [%[^]]]\n",
                  record.name, record.password, record.billing_address, record.phone_number,
                  &record.amount_paid, &record.amount_due, record.date) == 7)
    {
        if (strcmp(customer.name, record.name) == 0) {
            printf("P: %s\nD: %s", edited_details.phone_number, edited_details.date);
            fprintf(new_file, "[%s], [%s], [%s], [%s], [%lf], [%lf], [%s]\n", edited_details.name, edited_details.password, edited_details.billing_address, edited_details.phone_number, edited_details.amount_paid, edited_details.amount_due, edited_details.date);
        } else {
            fprintf(new_file, "[%s], [%s], [%s], [%s], [%lf], [%lf], [%s]\n", record.name, record.password, record.billing_address, record.phone_number, record.amount_paid, record.amount_due, record.date);
        }
    }

    fclose(file);
    fclose(new_file);

    remove(CUSTOMERS_FILE);
    rename("customers_new.txt", CUSTOMERS_FILE);

    printf("\nThe customer details have been successfully modified!\n");
    key_to_continue();
}

MODIFYING DETAILS
==============

CREATE A CUSTOMER PROFILE
=========================
Name (dumbfk): test
DATA: testPassword (abc123): lol
DATA: lolBilling Address (pukima jalan): lol
DATA: lolPhone Number (6969696969): 499449
DATA: 499449Amount Paid (   6969.00): 499449
Amount Due (6969699.00): 499494
Payment Date (6/9/1969): 22/2/2000
DATA: 22/2/2000P: �O���
D: �O���
The customer details have been successfully modified!

[well lol], [abc123], [wtf bro? 24], [0183188383], [3000.000000], [4000.000000], [12/12/2012]
[chow hai], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[lol head], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[stupid face], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[dumbfk], [abc123], [pukima jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]

[well lol], [abc123], [wtf bro? 24], [0183188383], [3000.000000], [4000.000000], [12/12/2012]
[chow hai], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[lol head], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[stupid face], [abc123], [lol jalan], [6969696969], [6969.000000], [6969699.000000], [6/9/1969]
[test], [lol], [lol], [�O���], [499449.000000], [499494.000000], [�O���]

正如您可能看到的，问题在于付款日期和电话号码字段变得混乱。它发生在我使用strcpy之后。我调试了

read\u string（..）

函数，它看起来很好。我不明白为什么会这样。如能帮助解决此问题，我们将不胜感激

有趣的是：只有

日期

和

电话号码

受到影响<代码>名称，

密码

，

账单地址

没有问题。

将read\u string函数中的本地字符数据更改为静态变量，以便不会丢失内存

  #define MAX_STR_LENGTH 100

 char* read_string(int length) 
 {
    static char data[MAX_STR_LENGTH]; // change to static -- it will not change
    rewind(stdin);
    fgets(data, length, stdin);

    if (data[0] == '\n') {
        data[0] = '\0';
    }

    strtok(data, "\n");

    printf("DATA: %s", data);

    return data;
}

这是一个非常好的例子，说明指针和数组不是一回事：

char* read_string(int length) {
    char data[length];
    // code
    return data;
}

将不起作用，因为

data

是在堆栈上分配的本地数组，当函数返回时将不再存在

如果您将

char data[length]

更改为

static char data[length]

，它将起作用。但是请注意，之前的读取将被覆盖，因此这将无法按预期工作：

char *s1, *s2;
s1 = read_string(10);
s2 = read_string(10);
printf("First string: %s\n", s1);
printf("Second string: %s\n", s2);

解决这个问题的一种方法是使用

char data*=malloc（length*sizeof*data）

。这样，您将能够使用以前的读取。但一般来说，您希望避免像这样隐藏的

malloc

s，因为您需要

free

它们。如果您想采用该解决方案，请执行以下操作：

char * read_string(char * dest, int length) {
    char data[length];
    // code
    return strncpy(dest, data, length);
}

char * str = malloc(length);
if(! read_string(str, length)) {
    fprintf(stderr, "Error reading string\n");
    exit(EXIT_FAILURE);
}
// Code
free(str);

然后这样称呼它：

char * read_string(char * dest, int length) {
    char data[length];
    // code
    return strncpy(dest, data, length);
}

char * str = malloc(length);
if(! read_string(str, length)) {
    fprintf(stderr, "Error reading string\n");
    exit(EXIT_FAILURE);
}
// Code
free(str);

另一个选项是将指针与长度一起传递

void read_string(char *data, int length) {

    fgets(data, length, stdin);

    if (data[0] == '\n') {
        data[0] = '\0';
    }

    strtok(data, "\n");

    printf("DATA: %s", data);

}

打电话给

 read_string(edited_details.name, 50);

那么就不需要使用strcpy（）

在C语言中没有对字符串的直接支持。大多数情况下，您必须处理（我应该说是“内存块”而不是“数组”？）包含字符的内存块以及最后的

NUL

在您的情况下，它是这样的：

char * read_string(char * dest, int length) {
    char data[length];
    // code
    return strncpy(dest, data, length);
}

char * str = malloc(length);
if(! read_string(str, length)) {
    fprintf(stderr, "Error reading string\n");
    exit(EXIT_FAILURE);
}
// Code
free(str);

将文件中的字符串（一定数量的字符）读入一块内存

您希望该内存块保持有效，直到你可以利用这个字符串

你用你的绳子。就是这样

第二个是你的代码中被破坏的部分

char* read_string(int length) {
    /* "data" is your chunk of memory. 
     * It is an array. 
     * This array is local to containing function.
     * This array is automatically allocated on the stack.
     * This array has its address in memory. Like &data[0].
     * The address may change from one invocation of the function to another.
     */
    char data[length];

    /* some code here... */

    return data; /* true, this returns the address &data[0] */
} 
/* The function is done. Local variables (array by the name of "data") are gone.
 * The memory on the stack that was once allocated for local variables is  
 * considered "free-to-use" by any other function you will invoke next. This memory
 * is not valid for use outside the function any more, but you may and you do
 * return a pointer to that memory, which is dangerous to use and harmful 
 */

基本上有三种方法可以解决此问题：

您可以声明一个全局内存块，例如一个全局数组：

char data[MAX_POSSIBLE_LENGTH];  /* Static storage. Global scope. */  
char* read_string() {
    /* some code here... */
    return data; 
}

。。。或者使用固定长度使阵列保持静态：

char* read_string() {
    static char data[MAX_POSSIBLE_LENGTH];  /* Static storage. Function scope. */  
    /* some code here... */
    return data; 
}

。。。或者从外部将阵列与其长度一起传入：

char* read_string(char *data, int length) {
    /* some code here... */
    return data; 
}

。。。或者使用动态分配

char* read_string(int length) {
    /* some code here... */
    char *data;
    data = malloc(length); /* Dynamic storage. Must be freed somewhere./* 
                           /* This is not an "array", now this really is a "chunk of memory" :) */

    return data; 
} 

void handle_modify_customer(Customer customer)
{
    Customer edited_details;
    char * input_str_ptr;

    printf("\nMODIFYING DETAILS\n==============\n\n");

    printf("CREATE A CUSTOMER PROFILE\n=========================\n");

    printf("Name (%s): ", customer.name);
    strcpy(edited_details.name, input_str_ptr = read_string(50));
    free(input_str_ptr); /* Don't allow mem leakage */

    /* ... */
}

@user3121023我使用退货吗？如何解决这个问题？

倒带（stdin）非常不可靠<代码>cat数据文件|您的程序

将破坏您的代码。您无法控制其他人如何调用您的程序。关于：

if（data[0]='\n'）{data[0]='\0'；}

这不是消除尾随换行符的方法。建议：

data[strcspn（data，“\n”）]='\0'请注意，这样使用static
会使代码不可重入且多线程不安全。