# 标准库stdlib.h函数system()

**函数原型**

```c
int system(const char* command);
```

**说明**

执行系统命令。

**参数**

```c
command: C-style字符串的命令, 或者一个空指针
```

**返回值**

如果command是一个空指针，则函数在命令处理器可用的情况下返回非零值，不可用的情况下返回零值。

如果command不是一个空指针，那么根据系统内执行的命令的结果返回。

**实例**

```c

#include <stdio.h>      /* printf */
#include <stdlib.h>     /* system, NULL, EXIT_FAILURE */

int main ()
{
  int i;
  printf ("Checking if processor is available...");
  if (system(NULL)) puts ("Ok");
    else exit (EXIT_FAILURE);
  printf ("Executing command DIR...\n");
  i=system ("dir");
  printf ("The value returned was: %d.\n",i);
  return 0;
}
```


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