PrequelCoding

Coder's Space

C String

What is String??



A string is a data type used in programming, such as an integer and floating point unit, but is used to represent text rather than numbers.

int x = 4;

char mystring[] = “prequel”;

Creating a String in C:

  • C has no special variable type for strings.
  • This standard library provides an extensive range of functions to handle strings.
  • Strings in C are stored in an array of type char.
  • Characters in a string are stored in adjacent memory cells one character per cell.
  • Ex: char myString[20];
  • We are just specifying the size but there is no specific data source.

Initializing a String in C:

  1. You initialize a string variable when you declare it
  2. char word[] = { ‘H’, ‘e’, ‘l’, ‘l’, ‘o’, ‘!’ };
  3. to initialize a string, it is the same as any other array initialization.
  4. In the absence of an array size, the C compiler automatically computes the number of elements in the array.
  5. Based upon the number of initializers
  6. This statement reserves space in memory for exactly seven characters.
  7. Automatically adds the null terminator.
  8. You can specify the size of the string explicitly just make sure you leave enough space for the terminating null character.
  9. char word[7] = {Hello!};
  10. So do not specify the size let the compiler figure out you can be sure it will be correct.
  11. You can initialize just part of an array of elements of type char with a string.
  12. char str[40] = ‘To be’;
  13. the compiler will initialize the first five elements, str[0] to str[4], with the character of the string constant
  14. str[5] will contain the null character ‘\0’.
  15. Space is allocated for all 40 elements of the array.

Example:

#include<stdio.h>
int main()
{
char str[] = "prequelcoding";

printf("%s", str);

return 0;
}

Displaying a string:

When we wanted to access a string which we store it in an array we simply use the name of the character in the form of input.

  • To display a string as output using printf function, you do the following:

printf(“\nThe message is: %s”, message);

  • %s is format specifier for outputting a null terminated string.
  • The printf function assumes when it encounters the %s format characters that the corresponding argument is a character string that is terminated by the null character.

//output

Inputting a string:

In C programming language we input a string or a statement using the scanf function which will produce us the desired output so let me just give you an example which will crystal clear the previous context.

#include<stdio.h>
#include<conio.h>
int main()
{
char str[10]; //storing a string in an array using char datatype

printf("hello world"); //we are trying to give the compiler our desired output
scanf("%s", str); //we  are trying to access the string which we have declared in the beginning of our code using char data type.
return 0;
}
In the code which we have declared here we are not using the and operand(&) which we use when are going to give the input because %s is itself a string specifier which takes care of the input statements.
Code for inputting string
Output of the string executed

Common String Functions:

  • We already know that a character string is a char array terminated with a null character (\0)
  • Character strings are commonly used.
  • C provides many functions specifically designed to work with strings.
  • Some of the commonly used strings are:
  • Getting length of a string
  • strlen
  • Copying one character string to another
  • strcpy() and strncpy()
  • combining two character strings together (concatenation)
  • strcat() and strncat()
  • determining if two character strings are equal
  • strcmp() and strncmp()

Getting Length of the String:

To determine the length of the string we need:

A character string

Strlength

Printf function

String.h library

#include<stdio.h>
#include<string.h> /* string header file library which consists of the string functions. */
int main()
{
char myString[] = "coder space";
printf("The length of string: %ld", strlen(myString));
return 0;
NOTE: if you are going to declare %d instead of %ld then you will be getting an error it is because we are here declaring strnlen() which is the sizeof data which will consist of a size_t return type.
So be careful while specifying the format ..

Output:

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