每天学点Linux--（File_status_flag和File_description_flag的区别/atoi函数的使用

一、




还是英文说的清楚些= =！
Note the difference in scope between the file descriptor flags and the file status flags. The former apply only to a single descriptor in a single process, whereas the latter
apply to all descriptors in any process that point to the given file table entry. When we describe the fcntl function in Section
3.14, we'll see how to fetch and modify both the file descriptor flags and the file status flags.

二、

atoi就是把字符串的数字转换成数字

int atoi(const char *nptr);

参数nptr字符串，如果第一个非空格字符存在，是数字或者正负号则开始做类型转换，之后检测到非数字(包括结束符
\0) 字符时停止转换，返回整型数。否则，返回零，

#include <stdlib.h>
#include <stdio.h>
int main(void)
{
float n;
char *str = "12345.67";
n = atoi(str);
printf("string = %s integer = %f\n", str, n);
return 0;
}

执行结果：

string = 12345.67 integer = 12345.0

#include <stdlib.h>
#include <stdio.h>
int main()
{
char a[] = "-100" ;
char b[] = "123" ;
int c ;
c = atoi( a ) + atoi( b ) ;
printf("c = %d\n", c) ;
return 0;
}

执行结果：

c = 23