C String: String Compare (Simple Note)

Simple Note

Code

#include <stdio.h>
#include <string.h>
/**
 * 
 * Tested with Dev-C++ 4.9.9.2
 *  
 * Practice of string compare.
 *
 * int strcmp ( const char * str1, const char * str2 );
 *             Compares the C string str1 to the C string str2.
 *             Returns an integral value indicating the relationship between the strings:
 *             A zero value indicates that both strings are equal.
 *             A value greater than zero indicates that the first character that does
 *             not match has a greater value in str1 than in str2; And a value less than zero
 *             indicates the opposite.
 * size_t strspn ( const char * str1, const char * str2 );
 *            Returns the length of the initial portion of str1 which consists only of characters that are part of str2.
 *            The length of the initial portion of str1 containing only characters that appear in str2.
 *            Therefore, if all of the characters in str1 are in str2,
 *            the function returns the length of the entire str1 string,
 *            if the first character in str1 is not in str2,
 *            the function returns zero.
 *             size_t is an unsigned integral type.
 *
 * References: 
 *         http://www.cplusplus.com/reference/cstring/strcmp/
 *        http://www.cplusplus.com/reference/cstring/strspn/
 * 
 */
int main () {
    // string
    char* chPtr = "abcdwxyz";
    int len;

    /** Compare whether two strings are
     * equal, grater than or less than
     */
    printf("chPtr equals to 'abcdwxyz'? \n%s\n", (strcmp(chPtr, "abcdwxyz") == 0? "true" : "false"));
    printf("chPtr larger than 'abcd'? \n%s\n", (strcmp(chPtr, "abcd") > 0? "true" : "false"));
    printf("chPtr less than or equal to 'abcd'? \n%s\n\n", (strcmp(chPtr, "abcd") <= 0? "true" : "false"));

    /** Use strspn to compare and find the different position
     *
     */
    len = strspn(chPtr, "abcdwxyz");
    printf("Are chPtr and 'abcdwxyz' equal? \n%s\n", (len == strlen(chPtr)? "true" : "false"));
    len = strspn(chPtr, "abcd");
    printf("Are chPtr and 'abcd' equal? \n%s\n", (len == strlen(chPtr)? "true" : "false"));
    printf("What is the first index (start from 0) that 'abcd' different with chPtr? \n%d\n\n", len);

    system("PAUSE");
    return 0;
}

Result

References

strcmp
http://www.cplusplus.com/reference/cstring/strcmp/

strspn
http://www.cplusplus.com/reference/cstring/strspn/

Download

Source code at github
https://github.com/benbai123/C_Cplusplus_Practice/blob/master/C_StringProcessing/string_compare.c