全WA，找不到问题求佬帮帮

#include <bits/stdc++.h>
#include <vector>
using namespace std;
 
int len(int a);
 
char p;//记录运算符 
int main()
{
	int i;
	cin>>i;
	int j;
	string z;
	int a,b,c; //仨数字 
	for(j=0;j<i;j++){
		getline(cin,z); 
		if(z[z.size()-1]=='\n'){
			z.resize(z.size()-1);//移除换行符 
		}
		if(z.size()==3){
			p=z[0];
			a=z[1]-'0';
			b=z[2]-'0';
		}
		else{
			a=z[0]-'0';
			b=z[1]-'0';
		}
		if(p=='a'){
			c=a+b;
			cout<<a<<"+"<<b<<"="<<c;
			cout<<"\n"<<len(a)+len(b)+len(c)+2<<"\n";
		}
		if(p=='b'){
			c=a-b;
			cout<<a<<"-"<<b<<"="<<c;
			cout<<"\n"<<len(a)+len(b)+len(c)+2<<"\n";
		}
		if(p=='c'){
			c=a*b;
			cout<<a<<"*"<<b<<"="<<c;
			cout<<"\n"<<len(a)+len(b)+len(c)+2<<"\n";
		}
	}
    return 0;
}

int len(int a){//求数字占位
	int le=0;
	if(a<=0){
		le++;
		a=-a;
	}
	while(a>0){
		le++;
		a=a/10;
	}
	return le;
}