How to Cut String C++

Question

Hello i want to cut string in this situation:

if (std::count(text.begin(), text.end(), ',') > 3 {
   //Cut String after 3 ',' 
}

text look like this:

"item1, item2, item3, item4, item5"

and i want this:

"item1, item2, item3, item4[Cut everything out on the right side >>], item5" and return "item1, item2, item3, item4"

Looking on first answer im looking for something like this(but working):

#include <string.h> 
#include <iostream> 
using namespace std; 

int main() 
{ 
    string s1 = "item1, item2, item3, item4, item5"; 

    if(std::count(s1.begin(), s1.end(), ',') > 3) {
        int comma = 0;
        int x = sizeof(s1);
        for(int i = 0; i < x; i++) {
            if (comma == 3) {
                string sub = s1.substr(0, i); 
                cout << "String is: " << sub; 
            }
            if(s1[i] == ',') {
                comma++;
            }
        }
    }
    return 0; 
} 

Answer 1

Look at std::string::substr

#include <string.h> 
#include <iostream> 
using namespace std; 

int main() 
{ 
    // Take any string 
    string s1 = "item1, item2, item3, item4, item5"; 

    // Start at position 0 to position of character ',' in "item4," 
    string sub = s1.substr(0, 26); 

    // prints item1, item2, item3, item4
    cout << "String is: " << sub; 

    return 0; 
} 

Answer 2

#include <string>
#include <algorithm>
#include <iostream> 
using namespace std; 

int main() 
{ 
    string s1 = "item1, item2, item3, item4, item5"; 

    if(std::count(s1.begin(), s1.end(), ',') > 3) {
        int comma = 0;
        int x = s1.length();
        for(int i = 0; i < x; i++) {
            if (comma == 3) {
                string sub = s1.substr(0, i-1); 
                cout << "String is: " << sub;
                return sub; 
            }
            if(s1[i] == ',') {
                comma++;
            }
        }
    }
    return 0; 
} 

Answer 3

There is no need to use std::count() , that is just wasted overhead. You are scanning the string twice when once would suffice.

Also, your use of sizeof() is wrong, you need to use std::string::size() instead. sizeof(s1) tells you the byte size of s1 (ie, of the std::string class itself) at compile-time, whereas s1.size() tells you how many characters are in s1 at runtime.

I suggest using std::string::find() in a loop, eg:

#include <string>
#include <iostream>

std::string cutAtNComma(const std::string &s, int n) {
    std::string::size_type idx = 0;
    while (n-- > 0) {
        idx = s.find(',', idx);
        if (idx == std::string::npos) break;
        if (n == 0) return s.substr(0, idx);
        ++idx;
    }
    return s;
}

int main() {
    std::string s1 = "item1, item2, item3, item4, item5";
    std::string sub = cutAtNComma(s1, 4);
    std::cout << "String is: " << sub;
    return 0;
}

Live Demo

Alternatively, you can use std::find_if() instead, eg:

#include <string>
#include <iostream>
#include <algorithm>

std::string cutAtNComma(const std::string &s, int n) {
    auto iter = std::find_if(s.cbegin(), s.cend(),
        [n](char c) mutable {
            if (c == ',') {
                if (--n == 0) return true;
            }
            return false;
        }
    );
    if (iter != s.cend()) return std::string(s.cbegin(), iter);
    return s;
}

int main() {
    std::string s1 = "item1, item2, item3, item4, item5";
    std::string sub = cutAtNComma(s1, 4);
    std::cout << "String is: " << sub;
    return 0;
}

Live Demo

Answer 4

You need to change little code as below.

#include <string.h> 
#include <iostream>
using namespace std; 

int main() 
{ 
    string s1 = "item1, item2, item3, item4, item5"; 
    int comma = 0;
    int x = s1.length();
    bool flag = false;
    for(int i = 0; i < x; i++) {
        if (comma == 4) {
            string sub = s1.substr(0, i-1); 
            cout << "String is: " << sub;
            flag = false;
            return 0;
        }
        if(s1[i] == ',') {
            comma++;
        }
        else{
            flag = true;
        }
    }
    if(flag)
        cout<<"String not contain more then 3 comma's \n String is :: "<<s1;

    return 0; 
}