NetNews Offline 2/NetNews Offline Volume 2.iso/news/comp/lang/c-part1/7782

Internet Message Format | 1996-08-05 | 2.5 KB

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From: Lawrence Kirby <[e-mail]>
Newsgroups: comp.lang.c
Subject: Re: How do I modify a character string that's declared as an array of char?
Date: Wed, 28 Feb 96 19:20:43 GMT
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References: <4gj2nl$[e-mail]> <4gjbjh$[e-mail]>
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In article <4gjbjh$[e-mail]>
           [e-mail] "Adam Peterson" writes:

>[e-mail] (Abu A. Wawda) wrote:
>
>>How do I write a function that can modify a string that was declared
>>as an array of characters?
>
>>for example:
>
>>myfunction(char **s)
>>{
>>       // modify string s

Since you are posting to comp.lang.c post valid C code. // may introduce a
comment in C++ but it is a syntax error in C.

>>}
>
>>main()
>>{
>>   char mydata[50];
>
>>   strcpy(mydata,"test string");
>>   myfunction(&mydata);
>>}

myfunction takes a pointer to a pointer but this is trying to pass it a
pointer to an array which is illegal in C (pointers and arrays are entirely
different things). Your compiler should have generated a warning or error
when compiling this.

>>this does not seem to work! it works fine if i pass i declare mydata
>>as a pointer to a character like this (or dynamically allocate the
>>string using a pointer) and pass the address of the pointer:
>
>>the problem with this is i need to write a function that will modify a
>>string created with an array of characters. i can't figure out how do
>>to this. please help. thanks!
>
>void myfunction(char *s)
>{
>        strcat(s,"more stuff"); // modify string s
>}
>
>void main()

In C main returns int. Writing void main() gives the compiler the freedom to
do anything it likes with the rest of the code - the whole program ceases
to have any meaning at all.

>{
>   char mydata[50];
>
>   strcpy(mydata,"test string");
>   printf(mydata);
>   myfunction(mydata);
>   printf(mydata);
>}
>
>The above does what I think you want to do.  When you call
>'myfunction', the '&' was not neccessary by definition, then *in*
>'myfunction', you were dropping two levels of redirection down.

I think you meant 'indirection'!

--
-----------------------------------------
Lawrence Kirby | [e-mail]
Wilts, England | [e-mail]
-----------------------------------------