C语言编写,输入一行字符(用回车结束),每个数字字符的前后都有空格.请编程,把这一行中的数字转换成一个整数

//---------------------------------------------------------------------------

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

int main(int argc, char* argv[])
{
char a;
int i=0;
while ((a=getchar())!='\n')
if (isdigit(a)) i=i*10+a-48;
printf("%d",i);
return 0;
}
//---------------------------------------------------------------------------

#include <stdio.h>
#include <string.h>
#include <ctype.h>
void main(){
char s[255], *t = s, *start = s;
int find_digit = 0;
long num = 0;
printf("Please input a strings(include digits): "); /* 请输入 1 个含有数字的字符串 */
gets(s);
printf("\n");
while (*t != '\0'){
if (isdigit(*t)){
if (!find_digit) start = t;
find_digit = 1;
t++;}
else if (*t == ' ') strcpy(t, t + 1);