Predefined function in string in c

Predefined functions in string

Introduction

Programming languages provide a number of predefined functions for working with strings. These functions can be used to perform a variety of tasks, such as copying, concatenating, searching, and comparing strings.

In this page, we will discuss some of the most common predefined functions in string.

Strcpy

The strcpy() function copies one string to another string. The syntax for the strcpy() function is as follows:

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

The strcpy() function takes two arguments:

• destination: The pointer to the destination string.
• source: The pointer to the source string.

The strcpy() function copies the characters from the source string to the destination string, until it reaches the null terminator character (\0).

Strcat()

The strcat() function concatenates two strings. The syntax for the strcat() function is as follows:

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

The strcat() function takes two arguments:

• destination: The pointer to the destination string.
• source: The pointer to the source string.

The strcat() function appends the characters from the source string to the end of the destination string.

strlen()

The strlen() function returns the length of a string. The syntax for the strlen() function is as follows:

size_t strlen(const char* string);

The strlen() function takes one argument:

• string: The pointer to the string.

The strlen() function returns the number of characters in the string, excluding the null terminator character.

strcmp()

The strcmp() function compares two strings. The syntax for the strcmp() function is as follows:

int strcmp(const char* string1, const char* string2);

The strcmp() function takes two arguments:

• string1: The pointer to the first string.
• string2: The pointer to the second string.

The strcmp() function returns an integer value, which indicates the relationship between the two strings:

• 0: The two strings are equal.
• A positive value: The first string is greater than the second string.
• A negative value: The first string is less than the second string.

Example

The following example shows how to use the strcpy(), strcat(), strlen(), and strcmp() functions:

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

int main() {
  char str1[100], str2[100], str3[200];

  printf("Enter the first string: ");
  gets(str1);

  printf("Enter the second string: ");
  gets(str2);

  // Copy the first string to the third string
  strcpy(str3, str1);

  // Concatenate the second string to the third string
  strcat(str3, str2);

  // Print the length of the third string
  printf("The length of the third string is %d.\n", strlen(str3));

  // Compare the first and second strings
  if (strcmp(str1, str2) == 0) {
    printf("The two strings are equal.\n");
  } else {
    printf("The two strings are not equal.\n");
  }

  return 0;
}

Output:

Enter the first string: Hello
Enter the second string: World
The length of the third string is 10.
The two strings are not equal.

Conclusion

Predefined functions in string are a powerful tool for working with strings. They can be used to perform a variety of tasks, such as copying, concatenating, searching, and comparing strings.

Further Reading:

Predefined function in string

function in c programming

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