String Handling C Language

String

In C programming, a string is a sequence of one or more than any characters terminated with a null character. In C language you can only save string in one dimensional character array , no separate data type for string like java or c#.

Declare a string

     char str = "GIRFA";

G

I

R

F

A

\0

Compiler will create an array of 6 element one extra cell for null character which is used to detect end of string.

Input/Output

char str[10];

     printf("Enter string>>");

     scanf("%s", str);

     for (i = 1; i<str[i] != '\0'; i++)

          printf("%c", str[i]);

This example shows you input a string without space and process each character.

     char str[10];

     printf("Enter string>>");

     gets(str);

     puts(str);

This example shows how to input space and print using library function.

C language compiler has reach variety of string handling functions string.h library file. Some popular function examples are given below.

1 strcpy

Copy a string into other

Declaration:

   char *strcpy(char *dest, const char *src);

   char far * _fstrcpy(char far *dest, const char far *src);

 Remarks:

Copies string src to dest, stopping after the terminating null character has

been moved.

int main(void)

 {

    char string[10];

    char *str1 = "abcdefghi";

    strcpy(string, str1);

    printf("%s\n", string);

    return 0;

 }

2. Strlen

Calculates length of a string

 Declaration:

   size_t strlen(const char *s);

   size_t far _fstrlen(const char far *s);

 Remarks:

strlen calculates the length of s.

 Return Value:

Returns the number of characters in s, not counting the terminating null

character.

int main(void)

{

   char *string = "Borland International";

   printf("%d\n", strlen(string));

   return 0;

}

3. strcat

Appends one string to another

 Declaration:

   char *strcat(char *dest, const char *src);

   char far * far _fstrcat(char far *dest, const char far *src);

 Remarks:

strcat appends a copy of src to the end of dest. The length of the resulting

string is strlen(dest) + strlen(src).

int main(void)

{

   char destination[25];

   char *blank = " ", *c = "C++", *turbo = "Turbo";

   strcpy(destination, turbo);

   strcat(destination, blank);

   strcat(destination, c);

   printf("%s\n", destination);

   return 0;

}

4.strcmp

strcmp compare two strings

 Declaration:

   int strcmp(const char *s1, const char*s2);

 Remarks:

 strcmp performs an unsigned comparison of s1 to s2. _fstrcmp is the far

version.

Return Value:

These routines return an int value that is

   <  0  if s1 <  s2

   == 0  if s1 == s2

   >  0  if s1 >  s2

int main(void)

 {

    char *buf1 = "aaa", *buf2 = "bbb", *buf3 = "ccc";

    int ptr;

    ptr = strcmp(buf2, buf1);

    if (ptr > 0)

       printf("buffer 2 is greater than buffer 1\n");

    else

       printf("buffer 2 is less than buffer 1\n");

    ptr = strcmp(buf2, buf3);

    if (ptr > 0)

       printf("buffer 2 is greater than buffer 3\n");

    else

       printf("buffer 2 is less than buffer 3\n");

    return 0;

 }

5. strrev

 Reverses all characters in s (except for the terminating null)

 Declaration:

   char *strrev(char *s);

   char far * far _fstrrev(char far *s);

 Remarks:

strrev and _fstrrev changes all characters in a string to reverse order,

except the terminating null character.

For example, it would change

  string\0

to

  gnirts\0.)

 Return Value:

strrev returns a pointer to the reversed string.

int main(void)

{

   char *string = "Borland International";

   printf("string prior to strlwr: %s\n", string);

   strlwr(string);

   printf("string after strlwr:    %s\n", string);

   return 0;

}

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