功 能: 取长整型绝对值

用 法: long labs(long n);

程序例:

#include <stdio.h>

#include <math.h>

int main(void)

{

long result;

long x = -12345678L;

result= labs(x);

printf("number: %ld abs value: %ld\",

x, result);

return 0;

}

l:long;

abs:absolute;