atoi函数的简单实现

#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>

#define N 100

int my_atoi(char *src)
{
int flag = 0;
int num = 0;
if(src[0] == '-')
{
flag = 1;
src++;
}
while(*src)
{
if(isdigit(*src))
{
num *= 10;
num += *src - '0';
src++;
}
else
break;
}
if(flag)
num = -num;
return num;
}

int main(void)
{
char *str = "1234.567";
printf("%d\n",my_atoi(str));
printf("%d\n",atoi(str));
return 0;
}