c++ uppercase to lowercase code example

Example 1: convert whole string to uppercase c++

#include<bits/stdc++.h> 
using namespace std; 
  
int main() 
{ 
    string s = "Viet Nam"; 
    transform(s.begin(), s.end(), s.begin(), ::toupper);  //uppercase
    cout << s << endl; 
    return 0; 
}

Example 2: how to compare lower case character to uppercase cpp

for(int i=0;i<str.size();i++){
int c = str[i]; 
        if (islower(c))  
            str[i] = toupper(c);
}

Example 3: convert from uppercase to lowercase c++

int i = 0;
    while(str[i])
    {
        if(str[i] == std::toupper(str[i]) && std::isalpha(str[i]) == 1024)
        str[i]+= 32;
        ++i;
    }

Example 4: convert letters to uppercase in c++

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

int main()
{
    char letter;

    cout << "You will be asked to enter a character.";
    cout << "\nIf it is a lowercase character, it will be converted to uppercase.";
    cout << "\n\nEnter a character. Press . to stop: ";

    cin >> letter;

    if(islower(letter))
    {
        letter = isupper(letter);
        cout << letter;
    }

    while(letter != '.')
    {
        cout << "\n\nEnter a character. Press . to stop: ";
        cin >> letter;

        if(islower(letter))
        {
            letter = toupper(letter);
            cout << letter;
        }
    }

    return 0;
}