argv problem warning error

[bos1234]

Assume, user types ./replace E XY test.txt
All instances of the letter E will be replaced by XY in file test.txt

The buffer is declared as char buffer[100].

So the buffer is as below

buffer
 
 0   1   2   3   4  5   6   7   8   9   10
[H]-[E]-[L]-[L]-[O]-[]-[W]-[O]-[R]-[L]-[D]

So in this case since buffer[1] identically equal to argv[1][0],
then set buffer[1] = argv[2] *error*

however, I am getting this error: assignment makes integer without cast .

How can I assign the contents of argv[2] to buffer[1]?

[ledow]

argv[2] is a char *.

buffer[1] is a char.

You're trying to put a pointer into something that's not. Hence the error. You can either dereference the pointer (*), or you can actually try not to cram a whole given string into a single char (in this case, you're trying to replace E with XY!).

The "without cast" part is a bit misleading but basically saying to you: "You're trying to cram something into some other type, and you haven't told me explicitly that you know what you're doing by using a cast."

[bos1234]

thanks.
Is the following picture correct?
http://i43.tinypic.com/2laaal3.png

Should I be using malloc for the buffer? Since I'm trying to store XY into one element

[ledow]

Yes, and maybe yes.

You could iterate through the source buffer and each time either copy the char into a new buffer (which will hold the final result), or copy what SHOULD replace it into the new buffer. You'll have to be careful because one of those buffers will be longer than your source (and you have no idea how much longer until you get there, so it will probably keep growing - realloc - or you'll have to allocate a HUGE buffer to take account of every possibility) and you'll be at different points in each (e.g. after the first replacement, your "new" buffer will be one char longer than your old one but you still have to copy things to the END of the buffer).

You can do without the buffers if you want to write to the output file character by character, but that's up to you.

Literally, I'd:

1) Read the next char.
2) If it's the char being replaced:
- Write the replacement string out to the file.
Otherwise:
- Write the char out to the file.
3) Close the file.

[bos1234]

I'm still finidng it difficult to compare the buffer with argv. I understand that they are different types

I tried strcpy(argv[2], buf[x]) == 0

but like the user above said, I'm trying to put two characters into one element

This is the code I have written so far. Just the bare essentials. Error is on line 23

http://codepad.org/LjkaDIeQ