A C Program to sort two strings

Lazaro Claiborn 0 214 Views

Here is just a simple program to sort two strings inputted from the user entered on the command line.

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

#define MAXBUFF 80
#define TRASHSIZE 200

/* Gets extra junk off stdin of size of TRASHSIZE */
void getJunk(void) {
 char junk[TRASHSIZE];
 fgets(junk,TRASHSIZE,stdin);
}

/* Converts upper case letters to lower case */
void toLower(char *str) {
 int len = strlen(str), i;
 for (i=0;i<len;i++)
  if (str[i] >= 65 && str[i] <= 90) 
   name[i] += 32;
}

/* Has the same effect as strcmp but I just decided to write my own and save compiler time */
int cmpstr(char *, char*);

int main() {
 char str1[MAXBUFF], str2[MAXBUFF];
 int len1, len2, i;

/* Get the two strings from the user */
 printf("Please enter a string: ");
 scanf("%s", str1);

 getJunk(); 

 printf("Please enter another string: ");
 scanf("%s", str2);

/* Convert both string to lowercase before comparing */
 toLower(str1);
 toLower(str2);

 i = cmpstr(str1, str2);

 if (!i)
  printf("%s is equal to %s", str1, str2);
 else if (i==1)
  printf("%s %s", str1, str2);
 else if (i==2)
  printf("%s %s", str2, str1);

 system("pause");
 return 0;
}

int cmpstr(char *str1, char *str2) {
 int len1, len2, i;
 
 len1 = strlen(str1);
 len2 = strlen(str2);

 for (i=0;i<len1 && i<len2;i++) {
  if (str1[i] < str2[i])
   return 1;
  else if (str[i] > str2[i])
   return 2;
 }
 return 0;
}
Member Avatar for John A
John A 1,896 Vampirical Lurker

>Has the same effect as strcmp but I just decided to write my own and save compiler time
Yes, it definitely saves a lot of compiler time when the thing doesn't even get to the linking stage. You've made one or two corrections, but the snippet still leaves much lacking, and overall a terrible piece of code.

The first is here:

/* Converts upper case letters to lower case */
void toLower(char *str) {
 int len = strlen(str), i;
 for (i=0;i<len;i++)
  if (str[i] >= 65 && str[i] <= 90) 
   name[i] += 32; /* 'name' has never been declared; change this to 'str' */
}

You've got another typo in your cmpstr function:

int cmpstr(char *str1, char *str2) {
 int len1, len2, i;
 
 len1 = strlen(str1);
 len2 = strlen(str2);

 for (i=0;i<len1 && i<len2;i++) {
  if (str1[i] < str2[i])
   return 1;
  else if (str[i] > str2[i]) /* change 'str' to 'str1' */
   return 2;
 }
 return 0;
}

Like ~s.o.s~ already stated in the previous thread, cmpstr should return the difference between the 2 strings instead of simply a 1 or 2, so as to make it nearly identical to the original strcmp funcition.

Secondly, your getJunk() function is very crude and limited -- what happens if there's more than 1 newline in the input buffer, or if there's nothing in there at all? It works in this case, but it should work in most cases. A better version can be seen here.

In fact, instead of using scanf for your input, you should rely purely on fgets() for your input. It's a much better input method because it does not have the constant problem of leaving behind newlines in the buffer. Also see this for even better detail on why scanf is bad. Here is how to do input properly with fgets:
http://www.daniweb.com/tutorials/tutorial45806.html

There's many more problems with your code, but hopefully this will give you a basic idea of what's wrong with your code.

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