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C program to convert lowercase string to uppercase

C program to convert lowercase string to uppercase

Write a C program to convert string from lowercase to uppercase string using loop. How to convert string from lowercase to uppercase using for loop in C programming. C program to convert lowercase to uppercase string using strupr() string function.

Logic to convert lowercase string to uppercase

Internally in C every characters are represented as an integer value known as ASCII value. Where A is represented with 65 similarly, B with 66.

    Input string from user, store it in some variable say str.
    Run a loop from 0 till end of string.
    Inside loop check if current string is lowercase then convert it to uppercase str[j] = str[j] - 32. Now, why subtracting it with 32. Because difference of a - A = 32.

Algorithm to convert lowercase to uppercase
%%Input : text {Array of characters / String}
         N {Size of the String}
Begin:
    For j = 0 to N do
        If (text[j] >= 'a' and text[j] <= 'z') then
            text[j] = text[j] - 32;
        End if
    End for
End

#include <stdio.h>
#define maxsize 100 // Maximum string size

int main()
{
    char str[maxsize];
    int j;

    /* Input string from user */
    printf("Enter your text : ");
    gets(str);

    for(j=0; str[j]!='\0'; j++)
    {
        /*
         * If current character is lowercase alphabet then
         * convert it to uppercase.
         */
        if(str[j]>='a' && str[j]<='z')
        {
            str[j] = str[j] - 32;
        }
    }

    printf("Uppercase string : %s",str);
    return 0;
}