C 为什么我在函数搜索_lastname中遇到分段错误?
以下程序接受来自学生姓名、姓氏和分数用户的数据。函数search_lastname应该搜索给定姓氏的记录。但这给了分割错误。另一个功能是打印记录,并为尚未添加到程序中的其他功能创建了切换案例C 为什么我在函数搜索_lastname中遇到分段错误?,c,pointers,segmentation-fault,malloc,dynamic-memory-allocation,C,Pointers,Segmentation Fault,Malloc,Dynamic Memory Allocation,以下程序接受来自学生姓名、姓氏和分数用户的数据。函数search_lastname应该搜索给定姓氏的记录。但这给了分割错误。另一个功能是打印记录,并为尚未添加到程序中的其他功能创建了切换案例 #include<stdio.h> #include<string.h> #include<stdlib.h> char **first_name, **last_name; float *score; int entry; void print(); void sear
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
char **first_name, **last_name;
float *score;
int entry;
void print();
void search_lastname(char search_last_name[21]);
int main()
{
int i,option;
char search_last_name[21];
do
{
printf("\nPlease indicate the number of records you want to enter (The minimum number of entries is 5) :");
scanf("%d",&entry);
}
while(entry<=4);
score=(float*)malloc(entry*sizeof(float));
first_name=(char**)malloc(entry*sizeof(char*));
last_name=(char**)malloc(entry*sizeof(char*));
for(i=0;i<entry;i++)
{
first_name[i]=(char*)malloc(21*sizeof(char));
last_name[i]=(char*)malloc(21*sizeof(char));
}
printf("Please input records of students (enter a new line after each record), with following format first name last name score \n");
for(i=0;i<entry;i++)
{
scanf("%s%s%f",&first_name[i],&last_name[i],&score[i]); /*Input of records itself*/
}
do
{
printf("\nPlease choose the appropriate options :"); /*Switch statement for choosing options.*/
printf("\nPrint records (press 1)\nAdd a new record (press 2)\nDelete records (press 3)\nSearch by last name (press 4)\nSort by score (press 5)\nSort by last name (press 6)\nFind Median score (press 7)\nExit the Program (press 0)");
scanf("%d",&option);
switch(option)
{
case 1 :print();
break;
case 2 :
break;
case 3 :
break;
case 4 :
printf("\n Please enter the last name you want to search: ");
scanf("%s",search_last_name);
search_lastname(search_last_name);
break;
case 5 :
break;
case 6 :
break;
case 7 :
break;
case 0 :
break;
default :
printf("\n Please enter a valid option.");
}
}
while(option>=1 && option<=7);
return 0;
}
void print()
{
int i;
printf("\n The records of students are as follows :");
for(i=0;i<entry;i++)
{
printf("\nFirst name:%s, Last name:%s, Score:%f\n",&first_name[i],&last_name[i],score[i]);
}
}
void search_lastname(char search_last_name[21]) /*Funtion to search by last name*/
{
int i,counter=0;
for(i=0;i<entry;i++)
{
if(strcmp(search_last_name,last_name[i])==0)
{
printf("\nFirst name:%s, Last name:%s, Score:%f\n",first_name[i],last_name[i],score[i]);
}
}
}
#包括
#包括
#包括
字符**名字,**姓;
浮动*分数;
整数输入;
作废打印();
无效搜索姓氏(字符搜索姓氏[21]);
int main()
{
int i,选项;
char search_last_name[21];
做
{
printf(“\n请指明要输入的记录数(最少输入5条):”;
scanf(“%d”,条目(&T);
}
而(entry您的问题在于函数的使用。您需要更改
scanf("%s%s%f",&first_name[i],&last_name[i],&score[i]);
到
如果没有长度修饰符,您的%s
说明符将无法分离输入字符串,因此会将内存区域过度写入分配的内存,从而导致未定义的行为
另外,强烈建议您检查scanf()
的返回值,以确保输入正确
注:
main()
的建议签名是intmain(void)
malloc()
和族的返回值
scanf("%20s %20s %f", first_name[i], last_name[i], &score[i]);