strcat() Function in C

Last Updated on March 30, 2023 by Prepbytes

The C programming language has a vast range of built-in functions that can be used to perform various tasks. One such function is the strcat() function. strcat function in C is used to concatenate two strings. Moving down the article, we will learn what is strcat function in C is, its syntax, the parameters of the strcat function in C, return value of the strcat function in C and we will also see an example demonstrating how to implement the strcat function in C.

What is the strcat() Function in C?

The strcat function in C is a built-in function that is used to concatenate two strings. In simpler terms, it takes two strings as input and combines them to form a single string. It is declared in the string.h header file and is widely used in software development and programming.

Syntax of strcat() Function in C

The syntax of the strcat function in C programming language is as follows:

char *strcat(char *destination, const char *source);

In the above syntax, pointers are used, or simply put the syntax can be as follows :

strcat(dest,src);

Parameters of strcat() Function in C

The strcat function in C programming language takes two parameters:

• destination: This is a pointer to the string where the concatenated string is to be stored. It should have enough memory allocated to store the concatenated string. The destination string is modified by the function.
• source: This is a pointer to the string that is to be concatenated. It is the string that will be appended to the destination string. The source string is not modified by the function. It is specified as a constant pointer to indicate that the function will not modify the source string.

Return Value of strcat() Function in C

The strcat() function in C programming language returns a pointer to the destination string, which is the same as the first parameter of the function.

This means that the function modifies the destination string and returns a pointer to the beginning of the concatenated string. This makes it easy to use the concatenated string in other parts of the program.

One important thing to note is that if the destination string is not large enough to hold the concatenated string, the behavior of the function is undefined. So, it is essential to ensure that the destination string has enough memory allocated before calling the strcat() function.

Implementation of strcat() Function in C

Here is an example of how to implement the strcat function in C programming language:

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

int main() {
   char str1[20] = "Hello ";
   char str2[20] = "PrepBytes!";

   strcat(str1, str2);

   printf("Concatenated string: %s\n", str1);

   return 0;
}

Output

Concatenated string: Hello Prepbytes!

In this example, the strcat function in C is used to concatenate two strings, "Hello " and "PrepBytes!", into a single string "Hello PrepBytes!". The function modifies the destination string, str1, and returns a pointer to the beginning of the concatenated string.

Uses of strcat() Function in C

The strcat function in C is used for string concatenation, which means joining two strings into one. Here are some common uses of strcat function in C:

• Concatenating strings: The most common use of strcat function in C is to concatenate two strings into one. For example, suppose you have two strings "Hello" and "PrepBytes", and you want to combine them into a single string "Hello World". You can achieve this by using the strcat function in C.
• Building file paths: Another use of strcat function in C is to build file paths by concatenating directory names and file names. For example, if you want to open a file named "test.txt" that is located in the directory "C:\data", you can concatenate these two strings using the strcat() function to create the full file path "C:\data\test.txt".
• Creating URLs: Concatenating strings is also commonly used in creating URLs. You can concatenate domain names and paths using the strcat() function to create the full URL.

Conclusion
In conclusion, the strcat function in C is a powerful tool that is used to concatenate two strings into one. It modifies the destination string and returns a pointer to the beginning of the concatenated string. It is important to ensure that the destination string has enough memory allocated to avoid any unexpected behavior.

FAQs

Here are some frequently asked questions about the strcat function in C.

Q1: What header file do you need to include to use the strcat() function?
You need to include the string.h header file to use the strcat() function.

Q2: Is the source string modified by the strcat function in C?
No, the source string is not modified by the strcat function in C.

Q3: Does the strcat function in C add a null character at the end of the concatenated string?
Yes, the strcat function in C adds a null character at the end of the concatenated string.

Q4: Can you concatenate more than two strings using the strcat() function?
No, the strcat function in C can only concatenate two strings at a time.

Q5: Can you concatenate an empty string using the strcat() function?
Yes, you can concatenate an empty string using the strcat() function.

Q6: Does the strcat function in C check for buffer overflow?
No, the strcat function in C does not check for buffer overflow.