case insensitive string comparison

[osiris07]

Hi I'm doing a project for my C programming class and I can't figure out this one part of the assignment. The teacher changed it on us the original assignment was to filter through text messages we are given to look for certain words and prevent it from sending if it met certain criteria. One of those criteria is that there cannot be 3 mispelled words and recently the teacher ran a program and noticed that it said that a certain word was wrong because it wasn't capitalized or something. Anyway now we must check each word but it must be case insensitive the only way I know how to check is using the string compare function which is case sensitive is there anyone who can shoot me some ideas Thanks.

[laserlight]

Suppose that both the strings are in the same case. You can then use strcmp(), right? So, you can reduce the problem to one of ensuring that the strings are in the same case and using strcmp().

[osiris07]

Yes but the thing is that we are going to be given random messages so we will have to make sure that it is in fact case insensitive. I cant really make a function that makes sure that all the words are capitalized or something.

[Bladactania]

I'm going to follow laserlights lead and not give you the answer...

However I will provide you with a hint.

You can't be sure of the capitalization of the message in it's original form. So you have to modify the message (or modify a copy of the message so the original isn't altered) so you KNOW what the case of the message is.

[laserlight]

I cant really make a function that makes sure that all the words are capitalized or something.

Ah, but you can

Check out the toupper() function from <ctype.h>

[Bladactania]

I guess he was going to give you the answer anyway ;P

[osiris07]

ahh so I could scan in the words and then use the toupper function not only on the text message but also on the dictionary words so that they should be exactly the same even if the dictionary says its lowercase or uppercase. Thanks guys I'll try that out.

[Bladactania]

You got it!

[cpjust]

An easier (although less portable) solution is to use the stricmp() on Windows or strcasecmp() on Linux...
Although for this assignment, it's probably better to do it yourself with toupper()...

[Mr.Pointer]

I once took a quiz that asked me to write a case-insensitive version of strcmp. What I did was to simply compare every pair of characters (one from each string) after I had converted them to uppercase.