String and Character Array in C

String is a sequence of characters that are treated as a single data item and terminated by a null character '\0'. Remember that the C language does not support strings as a data type. A string is actually a one-dimensional array of characters in C language. These are often used to create meaningful and readable programs.

If you don't know what an array in C means, you can check the C Array tutorial to know about Array in the C language. Before proceeding further, check the following articles:

• C Function Calls

• C Variables

• C Datatypes

• C Syntax Rules

For example: The string "home" contains 5 characters including the '\0' character which is automatically added by the compiler at the end of the string.

Declaring and Initializing String variables in C

Let's see how you can declare and initialize a string variable in C language.

// valid
char name[13] = "StudyTonight";        
char name[10] = {'c','o','d','e','\0'};      

// Illegal
char ch[3] = "hello";    
char str[4];
str = "hello";  

String Input and Output in C

• %s format specifier to read a string input from the terminal.

• But scanf() function, terminates its input on the first white space it encounters.

• edit set conversion code %[..] that can be used to read a line containing a variety of characters, including white spaces.

• The gets() function can also be used to read character string with white spaces

Let's see a code example now,

char str[20];
printf("Enter a string");
scanf("%[^\n]", &str); 
printf("%s", str);

We can also ue gets function to get the string as input.

char text[20];
gets(text);
printf("%s", text);

String Handling Functions in C

C language supports a large number of string handling functions that can be used to carry out many of the string manipulations. These functions are packaged in the string.h library. Hence, you must include string.h header file in your programs to use these functions.

The following are the most commonly used string handling functions.

There are many more String functions, but in this tutorial we will learn how to use the above mentioned string functions.

1. strcat() function

Syntax is:

strcat("hello", "world");

strcat() will add the string "world" to "hello" i.e ouput = helloworld.

2. strlen() and strcmp() function

strlen() will return the length of the string passed to it and strcmp() will return the ASCII difference between first unmatching character of two strings.

 int j = strlen("studytonight");
 int i=strcmp("study ", "tonight");
printf("%d %d",j,i);

12 -1

3. strcpy() function

It copies the second string argument to the first string argument.

let's see an example of strcpy() function,

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

int main()
{
    char s1[50], s2[50];

    strcpy(s1, "StudyTonight");     
    strcpy(s2, s1);     

    printf("%s\n", s2);
    
    return(0);
}

StudyTonight

4. strrev() function:

It is used to reverse the given string expression.

Code snippet for strrev():

#include <stdio.h>

int main()
{ 
    char s1[50]; 
  
    printf("Enter your string: "); 
    gets(s1);  
    printf("\nYour reverse string is: %s",strrev(s1)); 
    return(0); 
}

Enter your string: studytonight
Your reverse string is: thginotyduts

Related Tutorials:

• C Array

• C Functions

• C Pointers

• C Structures