我正在使用 C 进行一些学习,并且无法识别内存泄漏情况。
首先,一些代码:
我的主要功能:
#define FILE_NAME "../data/input.txt"
char * testGetLine( FILE * );
int testGetCount(void);
int main(void)
{
int count = 0;
FILE * fptr;
if ((fptr = fopen(FILE_NAME, "r")) != NULL) {
char * line;
while ((line = testGetLine(fptr)) != NULL) {
printf("%s", line);
free(line); count++;
}
free(line); count++;
} else {
printf("%s\n", "Could not read file...");
}
// testing statements
printf("testGetLine was called %d times\n", testGetCount());
printf("free(line) was called %d times\n", count);
fclose(fptr);
return 0;
}
和我的getline函数:
#define LINE_BUFFER 500
int count = 0;
char * testGetLine(FILE * fptr)
{
extern int count;
char * line;
line = malloc(sizeof(char) * LINE_BUFFER);
count++;
return fgets(line, LINE_BUFFER, fptr);
}
int testGetCount(void) {
extern int count;
return count;
}
我的理解是,free
每次我调用我的testGetLine
函数时,我都需要调用,我这样做了。据我所知,在一个有四行的简单文本文件上,我需要免费调用5次。我在以下输出中使用我的测试语句验证了这一点:
This is in line 01
Now I am in line 02
line 03 here
and we finish with line 04
testGetLine was called 5 times
free(line) was called 5 times
我遇到的麻烦是,valgrind 说我alloc
6次,而我只调用了free
5次。这是 valgrind 的截断输出:
HEAP SUMMARY:
in use at exit: 500 bytes in 1 blocks
total heap usage: 6 allocs, 5 frees, 3,068 bytes allocated
500 bytes in 1 blocks are definitely lost in loss record 1 of 1
at 0x4C2B3F8: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
by 0x4007A5: testGetLine (testGetLine.c:13)
by 0x400728: main (tester.c:16)
LEAK SUMMARY:
definitely lost: 500 bytes in 1 blocks
indirectly lost: 0 bytes in 0 blocks
possibly lost: 0 bytes in 0 blocks
still reachable: 0 bytes in 0 blocks
suppressed: 0 bytes in 0 blocks
我觉得我在内存管理方面遗漏了一些东西。valgrind 说我正在使用的第 6 个内存分配在哪里?我应该如何释放它?
跟进实施阿德里安的回答
testGetLine
调整:
char * testGetLine(FILE * fptr)
{
extern int count;
char * line;
line = malloc(sizeof(char) * LINE_BUFFER);
count++;
if (fgets(line, LINE_BUFFER, fptr) == NULL) {
line[0] = '\0';
}
return line;
}
main
while循环调整:
while ((line = testGetLine(fptr))[0] != '\0') {
printf("%s", line);
free(line); count++;
}
free(line); count++;