C Valgrind:条件跳转或移动取决于未初始化的值-打开文件
[编辑]:我添加了完整的代码 我必须在C语言的unix系统上创建一个简单版本的“grep”命令。一切正常,只有Valgrind说条件跳转或移动取决于未初始化的值。C Valgrind:条件跳转或移动取决于未初始化的值-打开文件,c,valgrind,C,Valgrind,[编辑]:我添加了完整的代码 我必须在C语言的unix系统上创建一个简单版本的“grep”命令。一切正常,只有Valgrind说条件跳转或移动取决于未初始化的值。 我想,它可能与我试图打开的文件有关。请参阅下面我的代码。 请注意,我不能在我的代码中使用。 我在Ubuntu上用叮当声编译代码: cc-pedantic-Wall-Werror-g-std=c99 grep.c-o程序 这就是瓦尔格兰德所说的: lukas@lukas-VirtualBox:~/Desktop/shared/Lab04
我想,它可能与我试图打开的文件有关。请参阅下面我的代码。
请注意,我不能在我的代码中使用
。我在Ubuntu上用叮当声编译代码:
cc-pedantic-Wall-Werror-g-std=c99 grep.c-o程序
这就是瓦尔格兰德所说的:
lukas@lukas-VirtualBox:~/Desktop/shared/Lab04/prg-hw04$ valgrind --track-origins=yes ./program Mem /proc/meminfo
==2588== Memcheck, a memory error detector
==2588== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==2588== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info
==2588== Command: ./program Mem /proc/meminfo
==2588==
==2588== Conditional jump or move depends on uninitialised value(s)
==2588== at 0x4C32D08: strlen (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==2588== by 0x4EBC9D1: puts (ioputs.c:35)
==2588== by 0x108970: check (grep.c:14)
==2588== by 0x108AA9: read (grep.c:50)
==2588== by 0x108B66: main (grep.c:71)
==2588== Uninitialised value was created by a heap allocation
==2588== at 0x4C2FB0F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==2588== by 0x108A04: read (grep.c:33)
==2588== by 0x108B66: main (grep.c:71)
==2588==
MemTotal: 10461696 kB
MemFree: 7701488 kB
MemAvailable: 8480772 kB
==2588==
==2588== HEAP SUMMARY:
==2588== in use at exit: 0 bytes in 0 blocks
==2588== total heap usage: 4 allocs, 4 frees, 2,700 bytes allocated
==2588==
==2588== All heap blocks were freed -- no leaks are possible
==2588==
==2588== For counts of detected and suppressed errors, rerun with: -v
==2588== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)
你能帮我找出这个问题吗?这是我的grep.c文件
#include <stdio.h>
#include <stdlib.h>
#define SIZE 100
int printed = 1; // return value -> 0 for patter found, 1 for pattern not found
char *pattern;
char *dest;
void check(char *line, int length, int size) {
for (int i = 0; i < length; i++) {
if (line[i] == pattern[0]) {
for (int j = 1; j < size && (i+j) < length; j++) {
if (line[i+j] == pattern[j]) {
if (j==size-1) {
printf("%s\n", line); // print line
printed = 0; // pattern found
goto END;
}
} else {
break;
}
}
}
}
END: ;
}
void read(void) { // read lines, then check individual lines
int c;
int lengthPat = 0;
while(pattern[++lengthPat] != '\0'); // check length of pattern - I can't use string.h library
FILE *file = fopen(dest, "r");
size_t size =100;
char *line = (char*)malloc(size * sizeof(char));
if (line == NULL) //succesfully created malloc?
exit(102);
int last = 0;
if (file != NULL) { // file succesfully opened
while ((c = getc(file)) != EOF) {
if (c != '\n') { // read line until \n
if(last ==size) {
char *p_line = realloc(line, 2*size*sizeof(char));
if (p_line == NULL)
free(line);
line = p_line;
size *= 2;
}
line[last++] = (char)c;
}
else { // end of line, check for pattern
check(line, last, lengthPat);
last = 0;
for (int i = 0; i < size; i++) {
line[i] = '\0';
}
}
}
fclose(file);
free(line);
}
else {
fprintf(stderr, "Error: Could not open file!\n");
}
}
/* The main program */
int main(int argc, char *argv[])
{
if (argc == 3) {
pattern = argv[1];
dest = argv[2];
read();
}
return printed;
}
#包括
#包括
#定义大小100
int printed=1;//返回值->找到图案为0,找不到图案为1
字符*模式;
char*dest;
无效检查(字符*行、整数长度、整数大小){
for(int i=0;i
“连接到文件”是关键
输入文件的行数超过100个字符。用动态增长的堆数组替换堆栈数组
size_t size =100;
char c_line = malloc(size);
...
if(last ==size)
line = c_line = realloc(c_line, size<<=1);
行
不是以null结尾的,因此使用printf是一个高级主题。我们这样做:
for (int k = 0; k < length; k++)
putc(line[k], stdout);
putc(line[k], stdout);
for(int k=0;k
问题是字符串行的末尾缺少空终止符\0
。
谢谢大家的帮助。欢迎来到StackOverflow。请查看如何提供一个。特别是,将check
包含在您发布的代码中(如果没有它,问题不可复制),或者完全删除(如果是),都会很有帮助。(你可能还发现了一些有趣的问题)。请将valgrind的实际错误陈述复制/粘贴到你的问题中。OT:关于:FILE*FILE=fopen(dest,“r”)代码>始终检查(!=NULL)来自fopen()
的返回值,以确保操作成功。如果未成功,则调用perror(“我的错误消息”)
要输出到stderr
,您的错误消息和系统认为发生错误的文本原因。OT:关于:if(c!=(int)'\n')
表达式:'\n'已经是int
,因此无需强制转换itOT:关于:if(argc==3){
如果函数参数argc
不是3怎么办?那么应该输出类似于以下内容的用法语句:fprintf(stderr,“用法:%s\n”,argv[0]);然后是exit(exit_FAILURE);`Where两者都exit()
和退出失败
在头文件中:stdlib.h
谢谢@Joshua。不幸的是,这没有帮助,请看我的第一篇文章,我做了编辑。@LAKY911:我想我找到了其余的。
for (int k = 0; k < length; k++)
putc(line[k], stdout);
putc(line[k], stdout);