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Compiler Error

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Hey! This bit of code is supposed to read the names in the command line and say hello to each of them in turn. This is done with a loop that repeats each string in the command line (argv) untill it has reached the total number of strings (argc). However, it will not compile. for the command line: projectname Jack Todd it should read: Hello Jack Hello Todd Not exactly sure where my error is. I'm compiling with Visual Toolkit 2003. Here's the code: #include <iostream> #include <cstring> using namespace std; int main (int argc, char argv) { for (int rep = 1, rep > argc, rep++); { cout << "Hello " << argv[rep]; }; return 0; }; Anyone got any answers? -TJ

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int main(int argc, char *argv[])

Is the proper prototype.

And the for statement should look something like

for (int rep = 1; rep < argc; rep++)

Notice no ; at the end! If you do this it will execute a blank statement each time through the loop.
You also shouldn't put a ; after a }.

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Original post by uavfun
You also shouldn't put a ; after a }.
It's not so much that you shouldn't as that it has no effect. The key here is learning the meaning of these statements, proper syntax, etc, etc.

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#include <iostream>
#include <cstring>
// Not needed in this case, but can't hurt
// See, the code doesn't actually construct any std::strings;
// "string literals" in C++ are (unfortunately, to some ways
// of thinking) still represented as char *'s.

using namespace std;

int main (int argc, char argv)
// As mentioned, needs to be 'char *argv[]'. An array of char *.
// 'char' is just a single letter. Actually, it's a number
// which is either between 0 and 255, or -128 and 127, depending
// on your implementation, which can be *interpreted* as a single
// letter. You start to get the idea of why std::string is a
// Good Thing(TM). Heh... Anyway, that causes a problem with the
// array dereferencing.


for (int rep = 1, rep > argc, rep++);
// As mentioned, get rid of that semicolon! It is legal in C++
// to have a for loop with an empty body, which is what that
// does. It's also legal to have {} around a block of code that
// doesn't need them; it creates a new variable scope.
// (probably more useful in C, where you don't have the same
// flexibility WRT where you declare your local variables.)

cout << "Hello " << argv[rep];
// Not mentioned yet, but you'll want an extra "<< endl" at the
// end of that << chain. 'endl' is a special object recognized by
// cout, which when output will:
// 1) write a newline
// 2) (important!) "flush" the stream.
// You could also do it with '<< "\n" << flush;' (but why?)
// A stream is "buffered" you see; it collects up some data
// in memory in a buffer, and only outputs when the buffer is
// full (i.e. it needs to make room) or is explicitly told to.
// It should also flush at the end of your program, but you
// don't really want to count on that.
// Again the semicolon isn't needed here, but this one won't
// do any harm (except the harm caused by more experienced
// programmers laughing at you ;) )
return 0;

}; // Ditto this one.

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Thanks for the help. It compiles just fine now, but the program still doesn't give me any output. Any suggestions.

Oh, and what is the signifigance of the * before the name of the prototype array?

Thanks again.


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char * means a pointer to a char. Suppose you have char *pc = "Hello!"; The compiler actually stores this as Hello! followed by a zero. pc points to the H; it knows where the end is because of the 0.

So argv[0], argv[1], etc. each point to the beginning of an argument.

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