How to Print Char Array in C

1. Use a Loop to Print Char Array in C
2. Use printf With %s Specifier to Print Char Array in C
3. Use puts to Print Char Array in C
4. Conclusion

In this article, we will introduce multiple methods on how to print a char array in C.

Use a Loop to Print Char Array in C

Using a loop is a versatile way to print the elements of a character array. It provides control over the printing process and allows for more complex formatting.

However, it’s essential to have a clear understanding of the array’s length to avoid going out of bounds and causing segmentation faults.

Use the for Loop

The for loop is an excellent choice when you know the length of the character array in advance. It allows you to iterate precisely the right number of times, ensuring that you access only valid elements.

In the following example, we demonstrate the for loop method by iterating six times over an array of six characters:

#include <stdio.h>
#include <stdlib.h>

#define STR(num) #num

int main(void) {
  char arr1[] = {'a', 'b', 'c', 'd', 'e', 'f'};

  printf(STR(arr1) ": ");
  for (int i = 0; i < 6; ++i) {
    printf("%c, ", arr1[i]);
  }
  printf("\b\b\n");

  exit(EXIT_SUCCESS);
}

Output:

arr1: a, b, c, d, e, f

Here are the steps involved in the code above:

In this example, the for loop method allows us to precisely control the number of iterations over the array, ensuring that we print each character without going out of bounds.

Use the while Loop

The while loop method is a more flexible approach when you may not know the array’s length in advance, but you need to ensure the loop stops at the correct point to prevent segmentation faults. Here’s an example:

#include <stdio.h>

int main(void) {
  char arr2[] = {'a', 'b', 'c', 'd', 'e', 'f'};
  int i = 0;

  printf("arr2: ");
  while (arr2[i] != '\0') {
    putchar(arr2[i]);
    i++;
  }
  printf("\n");

  return 0;
}

Output:

arr2: abcdef

Here’s the process involved in the code above:

Use printf With %s Specifier to Print Char Array in C

The printf function in C is a versatile tool for formatting and outputting data to the console. It can manipulate input variables using type specifiers and format them accordingly.

When it comes to printing character arrays, the %s specifier in printf plays a crucial role.

A character array in C is essentially a sequence of characters stored in memory. While it shares a structure similar to C-style strings, character arrays don’t always end with the null character '\0'.

In contrast, C-style strings terminate with a '\0' to signify the string’s end. When using printf to print character arrays, including the null byte ('\0') at the end of the array is crucial for proper output.

If you omit the null termination, printf may attempt to access memory regions beyond the array’s boundaries, leading to undefined behavior, crashes, or segmentation errors. Therefore, it’s essential to ensure that your character array is null-terminated for safe and predictable behavior when using %s with printf.

#include <stdio.h>
#include <stdlib.h>

#define STR(num) #num

int main(void) {
  char arr1[] = {'a', 'b', 'c', 'd', 'e', 'f'};
  char arr2[] = {'t', 'r', 'n', 'm', 'b', 'v', '\0'};

  printf("%s\n", arr1);
  printf("%s\n", arr2);

  exit(EXIT_SUCCESS);
}

Output:

abcdeftrnmbv
trnmbv

As you can see, when we print the arr1 that doesn’t have the null terminator, we will get more characters until the iteration reaches one null terminator, \0.

Here’s another example:

#include <stdio.h>
#include <stdlib.h>

int main(void) {
  char arr[] = {'H', 'e', 'l', 'l', 'o', '\0'};
  printf("%s\n", arr);

  exit(EXIT_SUCCESS);
}

Output:

Hello

In this example, we’ve defined a character array arr that represents the string Hello. The null character '\0' is included at the end to ensure proper termination.

As we can see, it printed the entire string Hello.

Provide Length Information With %s

In some cases, you might want to specify the length of the character array to be printed, even if it contains null termination. The %.*s specifier allows you to do just that by dynamically specifying the length during printing.

You can either hard-code the length as a number between the % and s, or you can use an asterisk * to take the length from a provided argument. Note that both methods include the . character before the number or asterisk in the specifier.

#include <stdio.h>
#include <stdlib.h>

int main(void) {
  char arr[] = {'H', 'e', 'l', 'l', 'o', '\0'};
  printf("%.3s\n", arr);    // Prints the first 3 characters: "Hel"
  printf("%.*s\n", 4, arr); // Prints the first 4 characters: "Hell"

  exit(EXIT_SUCCESS);
}

Output:

Hel
Hello

In the first printf statement, we use %.3s to print only the first three characters of the array arr. In the second printf, we use %.*s to specify the length as 4, printing the first four characters.

This flexibility can be useful when you need to extract substrings or print a portion of the character array.

Use puts to Print Char Array in C

While the printf function is a versatile tool for formatted output, the puts function offers a straightforward way to print strings and character arrays in C. What sets puts apart from other output functions like printf is its automatic appending of a newline character ('\n') to the end of the printed string.

This behavior is particularly useful when you want to print strings as separate lines, as it ensures proper formatting.

The puts function takes a character array, often representing a string, as its argument. This character array must be null-terminated, meaning it ends with a null character '\0' to denote the string’s conclusion.

puts(string);

When puts is called, it begins reading characters from the start of the character array and continues until it encounters the null character '\0'. During this process, each character is printed to the standard output.

After successfully printing all the characters from the character array, puts automatically appends a newline character '\n' to the output. This newline character ensures that the next output appears on a new line, making it suitable for printing strings as separate lines.

The puts function returns a non-negative integer if it succeeds, and it returns EOF (End of File) in case of an error.

Here’s an example of how to use puts to print a character array in C:

#include <stdio.h>

int main() {
    char str[] = "Hello, World!";
    char arr[] = {'H', 'e', 'l', 'l', 'o', '\0'};

    puts(str);
    puts(arr);
    return 0;
}

In this example, the character array str contains the string Hello, World!, and the character array arr contains {'H', 'e', 'l', 'l', 'o', '\0'}. The puts function is used to print str and arr.

When you compile and run this program, you will see the following output:

Hello, World!
Hello

The newline character is automatically added by puts, making the output well-formatted and easy to read.

Conclusion

In this article, we explored several methods for printing character arrays in C. We discussed using loops, the %s specifier with printf, and the puts function.

These methods provide diverse approaches to print character arrays effectively. When choosing a method, consider factors like null termination and formatting requirements to ensure successful character array printing in C.