The cmd closes without finishing the process in C++

Question

When I run the code below, it takes my input and then the cmd closes without giving any error, the same Logic is used to Java and it worked.

#include <iostream>
using namespace std;

int main(){
string s;
int l = s.length();
int i,flag = 0;
cin >> s;
char c;

for(i = 0; i < l; i++){

    while(i<l && s[i] <= '9' && s[i] >= '0'){
            char c = s[i];
            cout << c;
            i++;
            flag++;
    }
    if( flag > 0){
        flag = 0;
        cout << " ";
    }

}


return 0;

}

Answer 1

1. Just like nacho searles said, your console is closed because work is done. A cin.get() or other blocking code could keep console not closing.

2. Since C++ is pass by value by default, your assignment of l doesn't link to s.length() dynamically. Your for loop would run 0 times.

You may assign value to s before getting its length.

string s;
cin >> s;
int l = s.length();

3. It seems i isn't needed out of for loop, you may define i in for loop like for(int i = 0; i < l; i++) .

Answer 2

Add something like this before you return 0:

cin.get();

The console is getting closed before you are able to read the output.

Answer 3

Welcome to the SO!

It is okay that your program is closing after execution. It is closed because it riched the

return 0;

line. It automatically closes on this line.

Everything you should do to slow down the closing is to wait before

return 0;

You can wait user's input adding line this way:

cin >> s;
return 0;

It is the most common solution in your case.

Answer 4

So I have made some changes and the code worked.. Although the code ran, it still have errors.

cin >> s; was changed to getline (cin, s);

char c = s[i]; and cout << c; was changed to cout << s[i];