aoti--学会使用库函数（k&R）

#include <ctype.h>
#include <stdlib.h>
#include <stdio.h>
#include <assert.h>
#define OK 0
int myatoi(char *);
int improvedatoi(char *);
int main(int argc,char **){
printf("input string is :12345 and +123 and -456 and -1*891 and -*\r\n");
printf("%d\t%d\t%d\t%d\t%d\t\r\n",myatoi("12345"),myatoi("+123"),myatoi("-456"),myatoi("-1*891"),myatoi("-*"));
printf("%d\t%d\t%d\t%d\t%d\t\r\n ",improvedatoi("12345"),improvedatoi("+123"),improvedatoi("-456"),improvedatoi("-1*891"),improvedatoi("-*"));
getchar();
return OK;
}
int myatoi(char * s){
assert(s);
int i,n;
n = 0;
for(i = 0;s[i] >= '0' && s[i]<= '9';i++){
n=10*n+(s[i]-'0');
}
return n;
}
int improvedatoi(char * s){
assert(s);
int i,n,sign;
for(i=0;isspace(s[i]);i++){
;
}
sign =(s[i] == '-') ? -1 : 1;
if(s[i] == '+' || s[i] == '-')
i++;
for(n = 0;isdigit(s[i]);i++){
n=10*n+(s[i]-'0');
}
return sign*n;
}