编写一个c语言程序检测内存泄露

当涉及到内存泄漏时，我们需要使用一些工具来检测和解决这个问题。其中一个常用的工具是 Valgrind，它可以检测内存泄漏和其它内存错误。以下是一个简单的 C 语言程序，使用 Valgrind 来检测内存泄漏：

#include <stdlib.h>

int main() {
    int *ptr = malloc(sizeof(int));
    *ptr = 42;
    free(ptr);
    return 0;
}

在终端中运行以下命令：

valgrind --leak-check=full ./a.out

Valgrind 将会输出内存泄漏的详细信息，如果没有内存泄漏，它将会输出类似于以下的信息：

==12345== HEAP SUMMARY:
==12345==     in use at exit: 0 bytes in 0 blocks
==12345==   total heap usage: 1 allocs, 1 frees, 4 bytes allocated
==12345==
==12345== All heap blocks were freed -- no leaks are possible
==12345==
==12345== For counts of detected and suppressed errors, rerun with: -v
==12345== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

如果有内存泄漏，它将会输出类似于以下的信息：

==12345== HEAP SUMMARY:
==12345==     in use at exit: 4 bytes in 1 blocks
==12345==   total heap usage: 2 allocs, 1 frees, 8 bytes allocated
==12345==
==12345== 4 bytes in 1 blocks are definitely lost in loss record 1 of 1
==12345==    at 0x4C2FB0F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==12345==    by 0x4005B7: main (in /path/to/program)
==12345==
==12345== LEAK SUMMARY:
==12345==    definitely lost: 4 bytes in 1 blocks
==12345==    indirectly lost: 0 bytes in 0 blocks
==12345==      possibly lost: 0 bytes in 0 blocks
==12345==    still reachable: 0 bytes in 0 blocks
==12345==         suppressed: 0 bytes in 0 blocks
==12345==
==12345== For counts of detected and suppressed errors, rerun with: -v
==12345== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)

这个程序中没有内存泄漏，所以 Valgrind 输出了 "no leaks are possible" 的信息。