函数在c ++中的字符串中查找只能与第一个字符一起使用吗？

Question

I want to find a char in a string consists of numbers and chars , if it's found the program does some operations , but when I use function find() , it returns only true if the char I am looking for is ONLY at the beginning of the string !!!!!

Ex : This is part of the problem !
The user enters 3 strings s1 , s2 , s3 ; between the first 2 strings there's char 'a' = '+' and between s2 and s3 there's char 'b' = '=' (The 3 strings are supposed to be numbers ) but if s2 is a word that includes the letter 'm' , the program converts s1 and s3 into integeres and writes the full operation ex : if i/p is 3247 + 5machula2 = 3749 then o/p would be 3247 + 502 = 3749

Here's the problem I'm trying to solve http://www.spoj.com/problems/ABSYS/ and this part of my code which has the problem :

int T;
int x,y,z;
string s1 ;
string s2  , s3 ;
char a , b;
cin>>T;
for(int i=0 ; i<T ; i++)
{
         cin>>s1>>a>>s2>>b>>s3;


for (int k=0; k<s2.size(); k++)
{ 
    if (k==s2.find("m"))
    {     
        stringstream ss(s1);
        stringstream ss3(s3);

        ss>>x;
        ss3>>z;

        cout<<s1<<" "<<a<<" "<<z-x<<" "<<b<<" "<<s3<<endl;
    }   
    else break;       
}

This is a loop that loops on the second string and if it find a char 'm' it should do what's mentioned above , but the problem here is that it only works if 'm' is at the beginning of the string and no place else.

Answer 1

Your else break; prevents the loop from ever looping.

Answer 2

The reason it only works when it's at the beginning is because you break out of the loop if it isn't, so it has no chance to check the rest:

[first iteration]
if (0 == s2.find("m")) //if found at beginning
    //do stuff
else break; //exit loop if not found at beginning

Instead of the loop, if you're just trying to see whether there is an m, just use find() :

if (s2.find('m') != std::string::npos)
    //"m" found in string, do the operations on s1 and s3