Comparing strings

[JohnDeon]

Hey I got a question about comparing strings. I have a code similar to below:

typedef char * string;

void main()
{
char choice[10];
printf("Enter number:\n");
scanf("%s", choice);
int result = getnum(choice);
printf("Number: %d", result);
}
int getnum(char choice[10])
{
string numbers[] = {"zero","one", "two", "three", "four"};
int i;
for(i=0;i<5;i++)
{
if(strcmp(numbers[i], choice) == 0)
{
int result = i;
return result;
}
}
}

The purpose of the code above is basically to turn a string into a number. Here's the problem I'm having if the user enters a valid number (One of the numbers in the array string) then the result is correct however if the result is not in the array it still returns a "1" for some reason.

Any reason for this? I'm new to C programming so excuse my amateur script

[whiteflags]

It's actually undefined behavior. Since the user entered a string that matches none of the other options, the loop will finish completely and the function will end improperly without a return statement.

Here's a look at what your compiler should be saying about the code:

C:\Documents and Settings\User>gcc -c -Wall test.c
test.c:4:6: warning: return type of 'main' is not 'int'
test.c: In function 'main':
test.c:7:1: warning: implicit declaration of function 'printf'
test.c:7:1: warning: incompatible implicit declaration of built-in function 'pri
ntf'
test.c:8:1: warning: implicit declaration of function 'scanf'
test.c:8:1: warning: incompatible implicit declaration of built-in function 'sca
nf'
test.c:9:1: warning: implicit declaration of function 'getnum'
test.c: In function 'getnum':
test.c:18:1: warning: implicit declaration of function 'strcmp'
test.c:23:1: warning: control reaches end of non-void function

The very last warning is what I talked about. But ... they are all important.

[JohnDeon]

I'm using codeblocks and it shows me none of those warnings. But is there a way of making the function return a "-1" if the number is not valid? if I just put it at the end of the loop like so:

int getnum(char choice[10]){
string numbers[] = {"zero","one", "two", "three", "four"};int i;for(i=0;i<5;i++){
if(strcmp(numbers[i], choice) == 0){
int result = i;return result;
}else return -1;
}
}

It's going to return -1 after each position it checks in the array. Any way of overcoming this?

[whiteflags]

Yes you can make the function return -1 if the number is not valid.

int getnum(char choice[10])
{
   string numbers[5] = { /*....*/};
   int result = -1, i;
   
   for ( i = 0; i < 5; i++) {
      if (strcmp(numbers[i], choice) == 0) {
         result = i;
         break;
     }
   }
   return result;
}

Or anything logically the same will work.

I'm not sure why your code is so hard to read. Please indent in the future.