realloc（）泄漏内存
我有一个函数，它为字符串添加一个字符：
void AddChToString(char **str,char ch){ int len=(*str)?strlen(*str):0; (*str)=realloc(*str, len+2); (*str)[len]=ch; (*str)[len+1]='\0'; } 仪器（在mac上）和Valgrind表示行：（* str）= realloc（* str，len + 2）是泄漏内存。 这是realloc的实现问题吗？ 或者我使用不当？
这是Valgrind的输出：
==39230== 6 bytes in 1 blocks are definitely lost in loss record 1 of 7 ==39230== at 0x100018B2D: realloc (vg_replace_malloc.c:525) ==39230== by 0x100002259: AddChToString (in ./OpenOtter) ==39230== by 0x10000477B: QueryMapFromString (in ./OpenOtter) ==39230== by 0x100684CD2: ??? ==39230== by 0x100001FB0: RequestHandler (in ./OpenOtter) ==39230== by 0x100065535: _pthread_start (in /usr/lib/libSystem.B.dylib) ==39230== by 0x1000653E8: thread_start (in /usr/lib/libSystem.B.dylib) ==39230== ==39230== 9 bytes in 1 blocks are definitely lost in loss record 2 of 7 ==39230== at 0x100018B2D: realloc (vg_replace_malloc.c:525) ==39230== by 0x100002259: AddChToString (in ./OpenOtter) ==39230== by 0x10000298E: ParseHTTPRequest (in ./OpenOtter) ==39230== by 0x100004151: OpenRoutesFile (in ./OpenOtter) ==39230== by 0x10000142B: main (in ./OpenOtter) ==39230== ==39230== 45 bytes in 5 blocks are definitely lost in loss record 3 of 7 ==39230== at 0x100018B2D: realloc (vg_replace_malloc.c:525) ==39230== by 0x100002259: AddChToString (in ./OpenOtter) ==39230== by 0x10000298E: ParseHTTPRequest (in ./OpenOtter) ==39230== by 0x100001EB4: RequestHandler (in ./OpenOtter) ==39230== by 0x100065535: _pthread_start (in /usr/lib/libSystem.B.dylib) ==39230== by 0x1000653E8: thread_start (in /usr/lib/libSystem.B.dylib) ==39230== ==39230== LEAK SUMMARY: ==39230== definitely lost: 60 bytes in 7 blocks ==39230== indirectly lost: 0 bytes in 0 blocks ==39230== possibly lost: 0 bytes in 0 blocks ==39230== still reachable: 1,440 bytes in 4 blocks ==39230== suppressed: 0 bytes in 0 blocks
谢谢。
调用realloc本身并不会泄漏内存。 您应该确保重新分配的字符串的内存在不再需要后免费释放。
您的仪器是否表明存在实际泄漏或存在潜在泄漏？
如果 realloc()失败， 那么像你一样使用realloc()会泄漏内存。 在这种情况下，它将返回NULL但不会释放原始块。 因此，您将丢失指向块的指针，并且无法释放它（除非指针存储在其他位置）。
但这应该是罕见的（即，当你耗尽记忆时）。
如果这是您的工具所抱怨的，您应该能够通过以下方式修复泄漏警告：
void AddChToString(char **str,char ch){ int len=(*str)?strlen(*str):0; char* tmp = realloc(*str, len+2); if (!tmp) { // whatever error handling is appropriate } (*str)=tmp; (*str)[len]=ch; (*str)[len+1]='\0'; }
我不知道有关realloc实现问题，但是在这段代码中肯定存在内存泄漏的机会：来自realloc联机帮助页：
如果
realloc()失败，则原始块保持不变; 它没有被释放或移动。
并且，由于realloc在失败时返回NULL ，如果失败，则会丢失指向已分配的内存块的唯一指针，因此存在内存泄漏。
为了避免这个问题，你应该这样做：
char * temp=realloc(*str, len+2); if(temp==NULL) { /* handle the error in some way */ } else *str=temp;
尝试使用单独的变量重新分配，然后调用strcpy将str变量放入该空间，如下所示：
void AddChToString(char **str,char ch){ char *blah; int len=(*str)?strlen(*str):0; blah=realloc(NULL, len+2); strcpy(blah, str); (*str)[len]=ch; (*str)[len+1]='\0'; }