toupper() function in C (original) (raw)

Last Updated : 10 Jan, 2025

The **toupper() function is used to convert lowercase alphabet to uppercase. i.e. If the character passed is a lowercase alphabet then the toupper() function converts a lowercase alphabet to an uppercase alphabet. It is defined in the **ctype.h header file.
**Syntax:

int toupper(int ch);

**Parameter: It accepts a single parameter:

• **ch: This represents the character to be converted to uppercase.

**Returns: This function returns the uppercase character corresponding to the ch.

Below programs illustrate the toupper() function in C:
**Example 1:-

c `

// C program to demonstrate // example of toupper() function. #include <ctype.h> #include <stdio.h>

int main() { char ch;

ch = 'g';
printf("%c in uppercase is represented as  %c",
       ch, toupper(ch));

return 0;

}

`

Output

g in uppercase is represented as G

**Example 2:-

C `

// C program to demonstrate // example of toupper() function. #include <ctype.h> #include <stdio.h>

int main() { int j = 0; char str[] = "geekforgeeks\n"; char ch;

while (str[j]) {
    ch = str[j];
    putchar(toupper(ch));
    j++;
}

return 0;

}

`

**Note:

If the character passed in the toupper() is any of these three

1. uppercase character

2. special symbol

3. digit

toupper() will return the character as it is.

**Example :

C `

// C program to demonstrate // example of toupper() function. #include <ctype.h> #include <stdio.h>

int main() { int j = 0; char str[] = "GeEks@123\n"; char ch;

while (str[j]) {
    ch = str[j];
    putchar(toupper(ch));
    j++;
}

return 0;

} // code is contributed by codersaty

`