C String

The one dimensional array of characters followed by a null character \0 called as a string in C Programming. Let us see how to declare C string array, access elements or characters, print string characters with examples.

C string Declaration or Syntax

The syntax of a string in C Programming is as follows:

char Name [Size];

Name: Please specify the name. For example full_name, employee_name, etc
Size: Number of characters required for this plus one (\0). For example, Size =10, then it can hold 9 characters.

For Example, char full_name[50];. Here, full_name is the name and the size equals 50. It means, this allows a maximum of 49 characters

C String Initialization

There are multiple ways to initialize string C Programming

char name[] = “Tutorial Gateway”; // Declare without Size

char name[50] = “Tutorial Gateway”; // Declare with Size

Declare Characters Array

char name[] = {‘T’, ‘u’, ‘t’, ‘o’, ‘r’, ‘i’, ‘a’, ‘l’, ‘G’, ‘a’, ‘t’, ‘e’, ‘w’, ‘a’, ‘y’, ‘\0’};
char name[16] = {‘T’, ‘u’, ‘t’, ‘o’, ‘r’, ‘i’, ‘a’, ‘l’,’ G’, ‘a’, ‘t’, ‘e’, ‘w’, ‘a’, ‘y’, ‘\0’};

You can also declare it using pointers

char *str;
char *name = “hello world”;

C Program to Declare and Print Strings

In this program, We are declaring the string in possible ways. Next, we are using the printf statement to print the char array. I suggest you refer Arrays in C article.

You have to use %s to display the string as output. Or you use C Programming puts function.

#include  <stdio.h>

int main(int argc, const char * argv[]) {
    // Without Size
    char name1[] = "Tutorial Gateway";
    
    // With Size
    char name2[50] = "Tutorial Gateway";
    
    // Declare Characters Array
    char name3[] = {'T','u','t','o','r','i','a','l','G','a','t','e','w','a','y', '\0'};
    
    char name4[16] = {'T','u','t','o','r','i','a','l','G','a','t','e','w','a','y', '\0'};
    
    printf("Name1: %s \n", name1);
    printf("Name2: %s \n", name2);
    printf("Name3: %s \n", name3);
    printf("Name4: %s \n", name4);
    return 0;
}

Name1: Tutorial Gateway 
Name2: Tutorial Gateway 
Name3: TutorialGateway 
Name4: TutorialGateway

Allow Users to enter String from Command line

In this program, we are allowing users to enter their own text. Next, we are printing that user given sentences as output.

#include  <stdio.h>

int main(int argc, const char * argv[])
{
    char name1[50];
    printf("Please enter the Name : ");
    scanf("%s", name1);
    
    printf("Name: %s \n", name1);
    return 0;
}

Please enter the Name : TutorialGateway
Name: TutorialGateway

Access Elements of a Strings in C programming

You can use indexes to access individual characters. By this, you can insert, delete, or update any character at any given position.

#include  <stdio.h>

int main(int argc, const char * argv[])
{
    char name[50];
    int i = 0;
    
    printf("Please enter the Name : ");
    scanf("%s", name);
    
    while (name[i] != '\0')
    {
        printf("The Character at %d Index Position = %c \n", i, name[i]);
        i++;
    }
    return 0;
}

The analysis of the C string character array in iteration wise is as shown below

First Iteration : while (name[i] != ‘\0’)
Here, i value is 0. It means, name[0] = h So, condition is True
It will print that character along with the index position.
Next, i value will increment

Second Iteration: while (name[1] != ‘\0’)
while (e != ‘\0’) – Condition True

Third Iteration: while (name[2] != ‘\0’)
while (l != ‘\0’) – It means, Condition was True

Fourth Iteration: while (name[3] != ‘\0’)
while (l != ‘\0’) – Condition True

Fifth Iter: while (name[4] != ‘\0’)
while (0 != ‘\0’) – This condition is True

Sixth Iteration:while (name[5] != ‘\0’)
while (\0 != ‘\0’) – Condition is False. So, Compiler will exit from While loop

C String length

In this program, we are using the built-in function strlen to find the length of a string or char array.

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

int main(int argc, const char * argv[])
{
    char nam[50];
    
    printf("Enter the Name : ");
    scanf("%s", nam);
    
    float len;
    len = strlen(name);
    printf("The Length = %.f \n", len);

    return 0;
}

Enter the Name : sample
Length = 6

C String Functions

The following are the list of available string functions in C Programming

memchr: Find the first occurrence of a character and returns a pointer to it.
strcat: To concat or combine
strncat: This is the same as above. However, you can restrict the characters to add. It appends user-specified characters to the end.
strcmp: Used to compare two and check whether they are equal or not.
strncmp: This C string function is the same as strcmp. However, you can restrict the total number of characters to compare.
strcpy: Used to shallow copy
strncpy: This is the same as strcpy. However, you can restrict the number of characters to copy.
strcoll: Using LC_COLLATE settings, it will compare two
strlen: Finds the total characters or length of it.
strlwr: Converts to to lowercase
strpbrk:It finds the first character in the first one that matches any character in a second one.
strrev: Use this to reverse.
strupr: Converts it to uppercase