Question

Make your own version of the library function strcmp(s1, s2), which compares two
strings and returns –1 if s1 comes first alphabetically, 0 if s1 and s2 are the same, and 1
if s2 comes first alphabetically. Call your function compstr(). It should take two char*
strings as arguments, compare them character by character, and return an int. Write a
main() program to test the function with different combinations of strings. Use pointer
notation throughout.

Answer 1

Answer on Question#50602 – Programming - C++

Make your own version of the library function strcmp(s1, s2), which compares two strings and returns –1 if s1 comes first alphabetically, 0 if s1 and s2 are the same, and 1 if s2 comes first alphabetically. Call your function compstr(). It should take two char* strings as arguments, compare them character by character, and return an int. Write a main() program to test the function with different combinations of strings. Use pointer notation throughout.

Program:

#include <iostream>
#include <string>
#define MAX_LEN 100
using namespace std;
int compstr(char* s1, char *s2)
{
    int i;
    for (i=0; ; i++)
    {
        if ((s1[i] == '\0') && (s2[i] == '\0'))
            return 0;
        if (s1[i] == '\0')
            return 1;
        if (s2[i] == '\0')
            return -1;
        if (s1[i] < s2[i])
            return 1;
        if (s1[i] > s2[i])
            return -1;
    }
    return 0;
}
int main()
{
    char str1[MAX_LEN], str2[MAX_LEN];
    cout << "Input first string: ";
    cin >> str1;
    cout << "Input second string: ";
    cin >> str2;
    int res = compstr(str1, str2);
    if (res == 0)
        cout << "Strings are same";
    else if (res == 1)
        cout << "First string comes first alphabetically";
    else
        cout << "Second string comes first alphabetically";
    return 0;
}

Answer:

Input first string: alph2

Input second string: alph1

Second string comes first alphabetically

Input first string: al

Input second string: alph

First string comes first alphabetically

Input first string: alp

Input second string: alp

Strings are same

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