Strings in C

Concept

A string is a 1D array of characters terminated by a NULL character ('\0'). 

  0   1   2   3   4   5   6    7
 ________________________________
| P | r | o | g | r | a | m | \0 |
|___|___|___|___|___|___|___|____|

Syntax 

Declaring a string

char str[8];

str is the name of the string variable.str can store only 7 letters.1 byte is needed to store NULL character.

str stores the base address of a string.It is a constant pointer to the 0th element of string.

Initializing a string

char str[] = "Program";

You can access the string elements by str[i].

You can manipulate string element by saying str[i] = 'C'

char* str = "Program"

str is a pointer to string Program.

This will allow you to access the string but not manipulate string elements.

Accept a string from user

scanf("%s",str);

%s is format specifier for string.

But scanf cannot accept multiword string.So we use a library function 

gets(str);

Print a string 

printf("%s",str);

puts(str);

But puts cannot print a multiword string and it places the control on the next line.

Commonly used string functions

strlen(s)                                   Returns the length of string s (excludes null character).

strcat(dest,source)               Appends a copy of source to the end of dest.

strcpy(dest,source)              Copies source to dest.

strcmp(s1,s2)                         Returns 0 if s1==s2, <0 if s1<s2, >0 if s1>s2

strrev(s)                                  Reverses string s.

More

Without using library functions

Find length of string

Copy a string to another string

Reverse a string

Concat two strings

Compare two strings