求大Lao告知这个怎么写，我是刚学不久

求大Lao告知这个怎么写，我是刚学不久，请帮我看看谢谢，嗯嗯

#include <stdio.h>

int main()
{
    char str[9];
    int a, b, c, d;
    scanf("%s", &str);
    a = str[1]-'0';
    b = str[3]-'0';
    c = str[5]-'0';
    d = str[7]-'0';
    int num1 = a*10+b;
    int num2 = c*10+d;
    printf("%d*%d=%d", num1, num2, num1*num2);
    return 0;
}