How to find string length in C using strlen() function
What is Strlen() function?
In C programming, strlen is a standard library function defined in the string.h header file. The strlen() function is used to find the length of a null-terminated string.
The function takes a single argument, which is a pointer to the null-terminated string and returns the length of the string as an unsigned int. The length of the string is the number of characters in the string, not including the null terminator character ('\0').
In C, the strlen() function is used to find the length of a string.
Here is an example of how to use it:
The strlen() function is defined in the string.h header file, so the first step is to include this file in your program.
#include <string.h>
The strlen function takes a single argument, which is a pointer to the null-terminated string you want to find the length of. A null-terminated string is a sequence of characters terminated by the null character ('\0').
Here is an example string:
char str[] = "Hello, world!";
The strlen function can be called as follows:
int len = strlen(str);
This will store the length of the string in the integer variable len. The length of the string is the number of characters in the string, not including the null terminator character.
Finally, you can print the length of the string to the console using printf:
printf("The length of the string '%s' is %d\n", str, len);
This will print the length of the string along with the original string itself.
Let’s understand it by the complete example:
Example:
#include <stdio.h>
#include <string.h>
int main() {
char str[] = "Hello, world!";
int len = strlen(str);
printf("The length of the string '%s' is %d\n", str, len);
return 0;
}
Output:
The length of the string 'Hello, world!' is 13
Scope of strlen() function
The strlen() function is a standard library function in the C programming language and is also available in many other programming languages. It is used to determine the length of a null-terminated string, i.e., the number of characters in the string before the terminating null character ('\0').
The strlen() function takes a single argument, which is a pointer to the first character of the string, and returns an integer value indicating the number of characters in the string. The function does not count the terminating null character in the length of the string.
The strlen() function is typically used for working with character arrays, string literals, and C-style strings. It is not designed to work with other data types or structures.
It is important to note that the strlen() function only works with null-terminated strings, and attempting to use it with non-null-terminated strings or non-string data can result in undefined behavior. Additionally, the length of a string returned by strlen() does not include any padding bytes that may be present in the string.
Applications of strlen() function
The strlen() function is a very useful function in C, and it has many applications in programming. Here are some examples:
- String manipulation: The strlen() function is often used in string manipulation tasks, such as copying or concatenating strings. Knowing the length of a string is essential when performing these tasks.
- Input validation: When writing programs that accept user input, it's important to validate the input to ensure that it is within the expected range. The strlen() function can be used to check the length of user input and make sure that it doesn't exceed a certain limit.
- Text processing: Text processing applications often require the use of the strlen() function to find the length of strings or to determine the location of certain characters within a string.
- Memory allocation: When working with dynamic memory allocation in C, the strlen() function can be used to determine the amount of memory needed to store a string.
- Compression and decompression: In some compression algorithms, the length of the original data needs to be known in order to properly compress or decompress the data. The strlen() function can be used to determine the length of the original data.
In general, the strlen() function is a very versatile function that can be used in many different applications involving strings.