Convert char from lowercase to uppercase

This program is about converting a lowercase English character to its corresponding uppercase character. It is a simple hack but the C built-in function toupper is definitely faster than this one.

Last Reviewed and Updated on February 7, 2020
Posted by Parveen(Hoven),
Aptitude Trainer and Software Developer

Program to convert a lowercase character to uppercase.

Ask the user to enter an English character in lowercase. Write code to display it in uppercase.

int main()

    cout << "Enter lowercase character: ";

    char k;

    cin >> k;

    We have to add 'A' - 'a' to convert lowercase 'a'
    to uppercase 'A'. This same number should be
    added to every lowercase character
    to change it to its corresponding uppercase character.
    char output = k + ('A' - 'a');

    cout << "Uppercase = " << output << endl;

    return 0;


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This Blog Post/Article "Convert char from lowercase to uppercase" by Parveen (Hoven) is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Updated on 2020-02-07. Published on: 2016-03-18