String in C language

A string is a sequence of characters stored as an array of characters, terminated by a null character ('\0'). Strings are used to represent textual data and are an essential part of C programming. The standard C library provides various functions for manipulating strings, and string handling is a fundamental skill for C programmers.

Declaring and Initializing Strings:

Strings in C can be declared and initialized in several ways:

1) Character Array:

char greeting[6] = {'H', 'e', 'l', 'l', 'o', '\0'};

Alternatively, you can use a string literal for initialization:

char greeting[] = "Hello";

In this case, the size of the array is automatically determined by the length of the string literal plus one for the null character.

2) Pointer to a String:

char *greeting = "Hello";

This declares a pointer to the first character of the string literal.

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String Functions in C:

C provides several standard library functions for string manipulation. Here are some commonly used functions:

strlen (String Length):

#include <string.h>

size_t length = strlen(greeting);

This function returns the length of the string, excluding the null character.

strcpy (String Copy):

#include <string.h>

char destination[20];

strcpy(destination, greeting);

Copies the contents of one string to another.

strcat (String Concatenate):

#include <string.h>

strcat(destination, " World");

Concatenates (appends) one string to the end of another.

strcmp (String Compare):

#include <string.h>

int result = strcmp(greeting, "Hello");

Compares two strings lexicographically. Returns 0 if they are equal.

strchr (String Character):

#include <string.h>

char *position = strchr(greeting, 'l');

Finds the first occurrence of a character in a string.

strstr (String Substring):

#include <string.h>

char *substring = strstr(greeting, "llo");

Finds the first occurrence of a substring in a string.

Example:

Example: #include <stdio.h> #include <string.h> int main() { char greeting[] = "Hello"; // Print the original string printf("Original String: %s\n", greeting); // Find and print the length of the string size_t length = strlen(greeting); printf("Length: %zu\n", length); // Copy the string to a new destination char destination[20]; strcpy(destination, greeting); printf("Copied String: %s\n", destination); // Concatenate a new string strcat(destination, " World"); printf("Concatenated String: %s\n", destination); // Compare strings int result = strcmp(greeting, "Hello"); printf("Comparison Result: %d\n", result); // Find a character in the string char *position = strchr(greeting, 'l'); printf("Position of 'l': %s\n", position); // Find a substring in the string char *substring = strstr(greeting, "llo"); printf("Substring 'llo': %s\n", substring); return 0; } output: Original String: Hello Length: 5 Copied String: Hello Concatenated String: Hello World Comparison Result: 0 Position of 'l': llo Substring 'llo': llo

This example demonstrates the basic usage of strings in C, including initialization, manipulation, and the use of common string functions. Strings in C are null-terminated character arrays, and understanding how to work with them is fundamental for C programmers.