String Functions

The most commonly used :

• Find the length of a string: strlen
• Copy one string into another: strcpy
• Compare two strings: strcmp
  • To see if they are equal, (returns 0 if they're equal)
    since if(str1 == str2) just compares 2 addresses,
    which are never equal, but does not cause a syntax error.
  • Indicates lexicological order, appropriate for sorting
    returns negative if first string is less than the second,
    or positive if first string is greater than the second.
• Concatenate two strings: strcat

The Program

/**********************************************************
* Filename:      stringfuncs.c                                                
* Author:        Sue Bogar                                                   
* Date written:  11/28/97                                                    
* Modified:      09/26/05
* Section:       101
* EMail:         bogar@cs.umbc.edu
*
* Description:
*     This code shows use of the most common string functions.          
**********************************************************/

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

#define SIZE 25

int main ( )
{
    int length, comparison;
    char str1[SIZE] = "oranges";
    char str2[SIZE] = "apples";           
    char str3[SIZE] = " and ";
    char str4[SIZE];

    /* Example using strlen */
    length = strlen (str1);
    printf ("The length of %s is %d\n",                     
            str1, length);

    /* strcpy copies second string into the first */
    strcpy(str4, str1);
    printf ("Just executed strcpy: str4 = %s & str1 = %s\n",
             str4, str1);

    /* compare apples and oranges */
    /* strcmp can be used to check for equality or*/
    /* for order*/
    comparison = strcmp(str1, str2);
    if (comparison < 0)
    {
        printf("%s is less than %s\n", str1, str2);
    }
    else if (comparison > 0)
    {
        printf("%s is greater than %s\n", str1, str2);
    }
    else
    {
        printf("%s and %s are equal\n", str1, str2);
    }

    /* strcat appends second string to the end of the*/
    /* first one */
    strcat(str2, str3);
    printf("After the first concatenation:\n");
    printf("str2 is: %s\n", str2);
    strcat(str2, str1);
    printf("After the second concatenation:\n");
    printf("str2 is: %s\n", str2);

    return 0;
}

The Sample Run