#include <stdio.h>
int atoi(char *str);
//字符串转换成整数
int atoi(char *str)
{
int i = 0;
int num = 0;
int flag = 1;//正负标志
if(str[i] == '-')//有负号
{
flag = -1;
i++;
}
while(str[i] != '\0')
{
num = num * 10 + str[i] - '0';
i++;
}
return num * flag;
}
int main () {
char a[]="512";
int b=atoi(a);
int c =b-12;
printf("%d\n",c);
return 0;
}