Thread: very dumb question.

I have a question that I know is going to make me look stupid. Im trying to round a number up, and I've included this #include <math.h>. I've been searching for a long time and I can't see why my compiler keeps telling me Math.Ceiling is an underclared identifier. I've read that I should add "-lm" to something but I have been able to see what I should add it to. Im using the Microsoft Visual c++ 2005 express edition beta 2 compiler. Any ideas?

One,

Code:

#include <cmath>

And as far as syntax for ceil goes.

Code:

int rounded_num;

double num_to_round = 1.88;

rounded_num = ceil(num_to_round);

cout << rounded_num;

/OR, just

cout << ceil(num_to_round);

i knew this question would make me look dumb

thnx

Well for starters you can use <cmath> instead of <math.h> since you are dealing with c++. Second you can show your actual code. Third you can just use the ceil() function

Well I changed the code around, and now I no longer get that error. Instead I get an error saying its going to overload the function. Heres my code. Error is coming from the string file_content(string a){ function. This is my first time using c++ in a long time

Code:

// test.cpp : Defines the entry point for the console application.
// inluding all the required headers

#include "stdafx.h"
#include <string>
#include <fstream>
#include <iostream>
#include <cmath>

using namespace std;

//function prototypes and invalid
string file_content(string a);
string encrypt(string a);
string decrypt(string a);
void write_file(string a,string b);
bool invalid = false;
float password_index;
string password;

int main(){
	string content;
	string file;
	string input;
	if (invalid == true){
		invalid = false;
		goto again;
	}
	cout<<"Welcome to ascii encrypter and decrypter v1.0"<<"\n";
again:
	cout<<"please enter the file you wish to encrypt or decrypt : ";
	cin>>file;
	cin.get();
	cout<<"getting file content \n";
	content = file_content(file);
choice:
	cout<<"all file information has been found"<<"\n"<<"would you like to encrypt or decrypt this file? ";
	cin>>input;
	cin.get();
	if (input=="encrypt"){
		content = encrypt(content);
	}
	else if (input=="decrypt"){
		content = decrypt(content);
	}
	else {
		cout<<"your intention is unclear\n";
		goto choice;
	}
	cout<<"now writing to file\n";
	write_file(file, content);
	cout<<"writting is complete\n";
	cin.get();
	return 1;
}

string file_content(string a){
	string file;
	string backup;
	string buffer;
	ifstream b_file (a.c_str());
	if ( b_file.is_open() ){
		while ( !b_file.eof() ){
			b_file>>buffer;
			file += buffer;
			file += " ";
		}
		b_file.close();
		password_index = ceil(file.length()/2);
		return file;
	}
	else{
		b_file.close();
		cout<<"wrong file name or path\n";
		invalid = true;
		return "null";
		main();
	}
}

string encrypt(string a){
	for (int z =0;z<a.size();z++){
		if (a[z]%2 == 0){
			a[z] += 4*z;
		}
		if (a[z]%2 != 0){
			a[z] -= 4*z;
		}
	}
	return a;
}

string decrypt(string a){
	for (int z =0;z<a.size();z++){
		if (a[z]%2 == 0){
			a[z] -= 4*z;
		}
		if (a[z]%2 != 0){
			a[z] += 4*z;
		}
	}
	return a;
}

void write_file(string a,string b){
	ofstream b_file (a.c_str(), ios::trunc);
	for (int z =0;z<(b.size()-1);z++){
		b_file<<b[z];
	}
}

Compiled and ran fine for me(encrypted and decrypted properly). I am using VC++ 6.

Though:
#include "stdafx.h"
Is not needed/used.

What compiler are u using?

I am using VC++ 6.

It also compiles and runs fine in Dev-C++ (5.0 beta 9.2 (4.9.9.2)). Free:http://www.bloodshed.net/dev/devcpp.html

the #include "stdafx.h" is needed for the visual studio 2005 for some reason.

Ohh.

strange that it compiles fine in one, and not another?

Yes, I would say so.

But since it compiles fine on two other app's, I would guess it is yours (It is in Beta after all). Maybe somebody else would know. But, you are done, compile it with Dev-C++

The ambiguity is actually really easy to understand and fix. ceil() expects some type of floating point number. You are giving it an int. So it has to change the int into a floating point number. But which type ( float, double, long double)? An easy fix to that is just to do:

Code:

password_index = ceil(file.length()/2.0);

>> the #include "stdafx.h" is needed for the visual studio 2005 for some reason

I don't think it is needed if you pick the right project type. On your existing project, you can go to the project properties and turn off precompiled headers. On new projects, select Win32 Console Application, then in the wizard make sure to go to the application settings and select Blank Project. You will have to add your source file, but it will be blank and will not require the stdafx.h.

Thnx for all the suggestions and help.