strcpy() Function in C

Last Updated on March 30, 2023 by Prepbytes

C programming language provides a lot of functions that help developers to manipulate strings. The strcpy function in C is one such function, which is used to copy one string to another. Here, in this article, we will discuss and understand what the strcpy function in C is, the syntax of the strcpy function in C, the parameters, and the return value of the strcpy function in C. We will also look at some examples which demonstrate how to implement the strcpy function in C.

What is the strcpy Function in C?

The strcpy function in C is defined in the string.h header file and is widely used in C programs for string manipulation. It is used to copy the character array pointed to the source to the location pointed by the destination. In other words, it copies the source string (character array) to the destination string(character array).

Suppose we want to copy the content of one string to another without deleting the original string. We can use the strcpy function in C instead of looping statements. It will save us time and reduce the complexity of our C code.

Syntax of strcpy Function in C

The syntax of the strcpy function in C is

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

Here, the destination is the destination string where the source string will be copied and the source is the source string that needs to be copied. The strcpy function returns a pointer to the destination string.

Parameters of strcpy Function in C

The strcpy function in C has two parameters:

1. destination: It is a pointer to the destination string where you want to copy the source string. This parameter is of type char*.
2. source: It is a pointer to the source string that needs to be copied. This parameter is of type const char*.

The function copies all the characters from the source string to the destination string until it encounters a null character. The destination parameter must be large enough to hold the copied string.

Return Value of strcpy Function in C

The strcpy function in C returns a pointer to the destination string. This means that the destination parameter is modified and now contains the copied string.

Examples of strcpy Function in C

Here are some examples of using the strcpy function in C.

Example 1: Copying one string to another
This example demonstrates how we can use the strcpy function in C to copy one string to another. Below is the code implementation and explanation.

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

int main() {
   char str1[20] = "PrepBytes!!";
   char str2[20];
   strcpy(str2, str1);
   printf("str1: %s\n", str1);
   printf("str2: %s\n", str2);
   return 0;
}

Output

str1: PrepBytes!!
str2: PrepBytes!!

Explanation: In this example, we declare two character arrays str1 and str2 of size 20. We initialize str1 with the string "PrepBytes". We then copy the contents of str1 to str2 using the strcpy function in C.

Example 2: Initializing a string
We will see, in this example, how we can use the strcpy function in C to initialize a string. Below is the code implementation and explanation.

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

int main() {
   char str[20];
   strcpy(str, "PrepBytes!");
   printf("%s", str);
   return 0;
}

Output

PrepBytes!

Explanation: In this example, we declare a character array str of size 20. We then use the strcpy function in C to initialize str with the string "PrepBytes!". Finally, we print the contents of str to verify that the strcpy() function has successfully initialized the string.

Advantages of Using the strcpy Function in C

Here are some advantages of using the strcpy function in C:

• The strcpy function is part of the C standard library, which means it is widely available and simple to use.
• It provides a fast and efficient way to copy one string to another.
• It is simple to grasp and easy to implement.

Disadvantages of Using the strcpy Function in C

Here are some disadvantages of using the strcpy function in C:

• The strcpy function in C does not check whether the destination string has enough space to hold the source string, which can result in a buffer overflow and undefined behavior.
• If the destination string is not null-terminated, strcpy() will continue to copy characters until it reaches a null character in memory, which can cause segmentation faults.
• Strcpy function in C can be vulnerable to buffer overflow attacks if the size of the destination string is not known or is not properly checked.

Conclusion
In conclusion, the strcpy function in C is a built-in library function used to copy one string to another. It takes two parameters, the destination string and the source string. The function copies all the characters from the source string to the destination string until it encounters a null character. It returns a pointer to the destination string.

FAQs

Here are some FAQs about the strcpy function in C:

Q1: Does the strcpy function in C perform any memory allocation?
Ans: No, the strcpy function in C does not perform any memory allocation.

Q2: What is the difference between strncpy and strcpy function in C?
Ans: strcpy() copies the entire source string to the destination string while strncpy() copies a specified number of characters from the source string to the destination string.

Q3: Can the strcpy function in C copy a string to itself?
Ans: Yes, the strcpy function in C can copy a string to itself.

Q4: Can the strcpy function in C handle null strings?
Ans: Yes, the strcpy function in C can handle null strings.

Q5: Can the strcpy function in C handle special characters?
Ans: Yes, the strcpy function in C can handle special characters.