I little basic question

Hi! This is my code:

Code:

---

...
char tmpchar[255];
...
printf("Enter the filename: ");
fgets(tmpchar,MAXFILES,stdin);
strcpy(tmpchar,ws2_());
printf("%s\n",tmpchar);
....

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And this is my WhiteSpace2_ function:

Code:

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char *ws2_(void) {
char *ws2_tmpchar[255];
int i;
for(i = 0;i<=strlen(tmpchar);i++)
{
    if(strcmp(tmpchar[i]," ") == 0)
          strcat(ws2_tmpchar[i],"_");
    else
          strcat(ws2_tmpchar[i],tmpchar[i]);
}
return ws2_tmpchar;

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Ok, afaik this should work. But it doesn't and gcc gives me warnings:
cast to pointer from integer of different size
passing arg 1 of 'strcmp' makes pointer from integer without a cast
return from incompatible pointer type


Thats not good ;) . First: Why does tmpchar[i] does not work ? And why is the returning of ws2_tmpchar incompatible ?
Thx for attention, Demonus

>>char *ws2_tmpchar[255];
is an array of pointers, not an array of chars. Try
>>char ws2_tmpchar[255];

You're returning a pointer to a local variable, which will go out of scope after the function ends.

strcmp() compares strings. Lookup isspace() for testing a char for being a space, tab, newline etc.

There are other problems, see how you get on and post again when you have troubles.

Quote:

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Originally posted by Hammer
>>char *ws2_tmpchar[255];
is an array of pointers, not an array of chars. Try
>>char ws2_tmpchar[255];

You're returning a pointer to a local variable, which will go out of scope after the function ends.

strcmp() compares strings. Lookup isspace() for testing a char for being a space, tab, newline etc.

There are other problems, see how you get on and post again when you have troubles.

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Ok, nice thx, but thats not the problem. the problem is that

Code:

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char tmpchar[255];
char ws2_tmpchar[255];

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cannot be used in

Code:

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strcat(ws2_tmpchar[i],tmpchar[i]);

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My real question was: why ? :) but thx for pointing to the other errors ;)

demonus

Because strcat() is for strings (arrays of chars), not for single chars, which is what tmpchar[i] is.

>> Ok, nice thx, but thats not the problem.

Apparently it is a problem, because you go on to say:

>> char tmpchar[255];
>> char ws2_tmpchar[255];

The next problem is you can't return 'ws2_tmpchar' from the function. Why? When the function exits, that piece of memory becomes invalid. So either pass an array *into* the function or else make the array 'static' (or global).

Another problem:

>> char tmpchar[255];
>> fgets(tmpchar,MAXFILES,stdin);

If MAXFILES > 255, you will have an access violation in your program, and it will crash.

>> for(i = 0;i<=strlen(tmpchar);i++)

Here you are calling strlen() over and over, though the length of the string doesn't change. Call it once, and store that in a variable.

Here's an easy, reusable way to achieve your goal:

Code:

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char *
 replace(char str[], char find, char exchange)
{
 int index, length = strlen(str);

    for(index = 0; index < length; ++index)
    {
        if(str[index] == find)
          str[index] = exchange;
    }

 return str;
}

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Code:

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char *
 ws2_(char str[])
{
 return replace(str, ' ', '_');
}

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