Capitalize in C

Capitalize

in C

Welcome to the Capitalize in C page! Here, you'll find the source code for this program as well as a description of how the program works.

Current Solution

#include <ctype.h>
#include <stdio.h>
#include <string.h>

char *captialize(char str[])
{
    for (int i = 0; i < strlen(str); i++)
        if (i == 0)
            str[i] = toupper(str[i]);
        else
            continue;
    return str;
}

int main(int argc, char *argv[])
{
    if (argc == 2 && strlen(argv[1]) != 0)
        printf("%s\n", captialize(argv[1]));
    else if (argc > 2)
        printf("Use quotes around multiple strings.\n");
    else
        printf("Usage: please provide a string\n");

    return 0;
}

Capitalize in C was written by:

• Jeremy Grifski
• Softizo
• Ștefan-Iulian Alecu

This article was written by:

• Jeremy Grifski
• shubhragupta-code
• Ștefan-Iulian Alecu

If you see anything you'd like to change or update, please consider contributing.

How to Implement the Solution

Header files

#include <ctype.h>
#include <stdio.h>
#include <string.h>

These lines import standard libraries so we can use built-in functions.

• <ctype.h> provides character functions like toupper().
• <stdio.h> provides input/output functions like printf().
• <string.h> provides string utilities like strlen().

Main function

int main(int argc, char *argv[])

This is where every C program starts. Here, argc represents the number of command-line arguments, and argv represents an array of strings containing those arguments. So, if we run:

./capitalize "hello"

then:

• argc = 2
• argv[0] = "./capitalize"
• argv[1] = "hello"

Input validation

if (argc == 2 && strlen(argv[1]) != 0)

This ensures:

• exactly one argument is provided
• it is not an empty string

If the user provides no input, the program prints usage message. If there are too many arguments, the program warns about quotes, because the user most likely called the program using ./capitalize hello world instead of ./capitalize "hello world".

Capitalization step

printf("%s\n", capitalize(argv[1]));

If input is valid, we call capitalize() with the first argument, then print the result. In the function:

char *captialize(char str[])
{
    for (int i = 0; i < strlen(str); i++)
        if (i == 0)
            str[i] = toupper(str[i]);
        else
            continue;
    return str;
}

we traverse each letter in the string. If i = 0, then we capitalize the first letter of the string using toupper, otherwise the string remains the same.

How to Run the Solution

If we want to compile and run the program on a computer, we first need a C compiler installed. Common choices include GCC, Clang, and Microsoft Visual C++ (MSVC).

Once a compiler is available, we can open a terminal in the same directory as the source file and compile the program.

For example, using GCC:

gcc -o capitalize capitalize.c
./capitalize

or using Clang:

clang -o capitalize capitalize.c
./capitalize

On Windows with the Microsoft compiler:

cl capitalize.c
capitalize.exe