C++ :: Declaring Variables In A Function?
Nov 12, 2012
This is a c program that is failing to compile. The error occurs in the calcLabs() function. The error called out is (btw, I'm using VS 2010): Error4error C2143: syntax error : missing ';' before 'type'
I don't understand why the compiler is not letting me declare variables in the calcLabs() function!
Code:
#include<stdio.h>
#include<stdlib.h>
void calcPercent(double *);
double calcLabs();
double calcExams();
double calcFinal();
char calcLetter(float);
[code]...
View 5 Replies
ADVERTISEMENT
Aug 9, 2013
I really do not see the difference between these two declarations:
int myvariable;
int * mypointer;
It is said that when you define a pointer, instead of containing actual data, it contains a pointer to the memory location where information can be found.
But doesn't the other variable declaration do the same? It obviously doesn't have data either. And it must be stored in a memory location as well. So I do not see the difference.
View 6 Replies
View Related
Jan 22, 2014
I am looking for a way to declare variables at run time which being a static language shouldn't happen. I will explain my situation.
I am upgrading a legacy program that modifies executables (non malicious). I am trying to add 64bit support.
It is a huge project and I understand the majority of it but my issues with how it handles the input data.
It has a struct that certain parameters of the input file is loaded into:
Code:
typedef struct DATA {
DWORD Size;
IMAGE_NT_HEADERS32 Headers;
} _DATA; *PDATA
etc, etc its a huge list.
My problem lies in the fact that I need to change IMAGE_NT_HEADERS_32 to IMAGE_NT_HEADERS64 at runtime.
That DATA struct gets called at least 110 times during runtime.
How I might tackle this? Having a conditional statement repeated that many times seems ridiculous.
View 6 Replies
View Related
Sep 30, 2014
I have created a windows form project in visual studio so that I can use a windows form to interact with the game class that I'm creating, but I'm running into some problems.
For one thing, I would like to be able to call Image::FromFile() one time only during initialization, and store the result in a member variable (called mBGImage). From what I can tell, the variable needs to be of type String^ (this caret symbol is new to me, but I understand it is the "managed code" version of the standard pointer, which would look like String*).
When I try to compile the following code (located in my header file) I get the error :
"error C3265: cannot declare a managed 'mBGImage' in an unmanaged 'BSG::BSGame'".
How can I store the result of Image::FromFile() permanently in my class?
When I try to declare a global variable of type "Image^", I get "error C3145: global or static variable may not have managed type System:rawing::Image ^"
#include "stdafx.h"
using namespace System;
using namespace System::ComponentModel;
using namespace System::Collections;
using namespace System::Windows::Forms;
[Code] ......
View 2 Replies
View Related
Jun 5, 2013
I am a bit confused about how specific one must be with arguments when declaring a function. I'll show you two functions from the book I'm using to learn C to show you what I mean.
Example 1 (greatest common denominator function):
Code:
void gcd (int u, int v) {
int temp;
printf ( "
[Code] ....
So in that function, there are exactly two arguments, because that's how many arguments the algorithm to find the gcd takes. No problem there, makes sense to me. Then further in the chapter on functions I run into this,
Example 2 (square root function):
Code:
float absoluteValue (float x) {
if ( x < 0 )
x = -x;
return x;
[Code] ....
In this second example, we have a square root function that is preceded by an absolute value function. The absolute value function has the one argument, "float x", however when this function is called within the square root function, the arguments "guess * guess * -x" are passed to it. I'm confused how this absolute value function is working with all of that inside it, when it was originally declared with just "x." The only possibility I can think of is that this expression is treated as a single unit, but I'm not sure.
View 2 Replies
View Related
Sep 14, 2013
I have a function
Code:
int exec_program(char * arguments[])
{
...
}
I can call it like this without a problem:
Code: char * uselessvariable[] = {"/bin/echo", "Testing", NULL};exec_program(uselessvariable);
However I get an error if I try to compile it like this:
Code: exec_program({"/bin/echo", "Testing", NULL});
How, in c, I can put this array inside of the argument in one line without having to name a new variable name?
View 2 Replies
View Related
Oct 23, 2013
I'm just wondering, why you have to set the length of the inner arrays declaring a function. In which moment does the code needs to be sure about the length of the inner arrays accessing an cell?
I came up with this question realizing the elements of the outer array beeing pointers to the first value of each inner array. Therefore I can access e.g. the first first element of the second inner array like this:
**(arr + 1) ...regardless of the length of any array to my mind.
parallel post: [URL]...
View 6 Replies
View Related
May 24, 2013
I am having following pointer variable declaration
Code: Static double (*funcs[]) (double) = { sin,cos,tan,asin,acos};
Here funcs is an array of pointers to functions which take double as input and gives double as output with static as storage type am I right.
View 2 Replies
View Related
Oct 28, 2013
so in declaring a display function prototype only that displays a student test scores in the format (student name tab number of scores tab test scores )
is this right?
#ifndef STUDENTTESTSCORES_H
#define STUDENTTESTSCORES_H
#include <string>
using namespace std;
class StudentTestScores{
private:
[Code]...
and also how do we call the display function if it is in a class from the header file onto the main cpp file.
View 2 Replies
View Related
Mar 29, 2014
ok I have a class Player with lots of variables and im gonna call a function to checkXp, if I call it with the whole player object does it use a lot more memory then if I just passed the couple things I need?
ex
checkXP(Player* play) // this is a whole object of player
or
checkXP(play->getXP(), play->getLVL()) // the variables I want.
I just realized I may not be able to modify anything from player in the checkXP() function
question 1: does passing the whole object use more memory
question 2: if I passed as just the variables I need, I wont be able to modify anything of object play?
View 1 Replies
View Related
Jan 24, 2015
In my program I created three separate return functions. Each function is labeled:
int boxes(int x, int y);
int leftOver(int x, int y);
double avgItemsShipped(int x, int y, int z);
Is it bad programming practice to use 'x' and 'y' in all of my functions? Should I use the this keyword inside the function? We use this often in my Java class and I know it exists in C++, but I haven't actually seen it used (or used it myself yet).
View 3 Replies
View Related
Mar 26, 2013
The following function uses reference variables as parameters. Rewrite the function so it uses pointers instead of reference variables, and then demonstrate the function in a complete program.
int doSomething(int &x, int &y)
{
int temp =x;
x = y * 10;
y = temp * 10;
return x + y;
}
I understand how to covert the reference variables to pointers, however I am stuck on this error. Either I get the error listed in the title or (with a few changes) the error "invalid conversion from 'int' to 'int*'"
What am I doing incorrectly?
#include <iostream>
using namespace std;
int doSomething(int*, int*);
int main(){
int X, Y, result;
[Code] ....
I have multiplied both x and y by 10 and then added them together!
Here is the result " //I really didn't know how else to use the "doSomething" function in a meaningful way. So... I just stated what the function does.
<< result << ".
";
system("PAUSE");
return 0;
}
int doSomthing(int *x, int *y)
[Code] .....
View 1 Replies
View Related
Feb 9, 2013
I am trying to display a variable from a class function the code works in debug but the variable is not displayed. Here is my code so far.
#include <iostream>
#include <string>
using namespace std;
class dayType {
public:
string day;
void setday(string);
[Code] .....
View 2 Replies
View Related
Dec 12, 2013
How to use a function twice to calculate two different variables. How to have a function compute the city tax, then it uses the function a second time to compute the county tax.
My program compiles, and runs fine, however it only outputs the city tax calculation. It seems it never attempts to calculate the county tax.
One thing: All of the directives I used is what we are limited to, no more, no less. He requires a set format and will dock points of you use anything but those directives and void main().
Here is my code so far:
/* function for city tax calculation */
#include <iostream>
using namespace std;
#include <string>
#include <cstdlib>
#include <cmath>
#include <iomanip>
const double city_tax_rate=0.03;
[Code] ....
I am using Visual studio 2010.
View 9 Replies
View Related
Jul 8, 2013
It is said that variables in a function cannot be changed by another function. Only by using pointers can variable values be changed. I am writing some functions to try to prove this theory, but I can't get it right.
Code:
#include <stdio.h>
#include <stdlib.h>
int main(void){
int x = 10;
printf("default x value is %d ",x);
[Code] ......
Code:
#include <stdio.h>
void try1(int x){
printf("x in try1 is %d
", x);
x++;
printf("x in try1 after ++ is %d
[Code]...
View 13 Replies
View Related
Mar 1, 2013
I am developing a program that will read a function (x^2+2x+4 or other function) and then comparing and start assigning variables. My idea is with an array:
int i,x;
char xs;
char function[20];
cin.getline(function, 20);
cout << "Your function is: ";
[Code] .....
Well this is my basically idea, but when the program detect an ^ this will be associate with the exp(x,n); well in general the user enter a function: x^3+3x^2+4x-8 give a value for x for example 3 and the program will convert in -- exp(3,3)+3*exp(3,2)+4*3-8 --, but I don't know how.
View 2 Replies
View Related
Oct 22, 2013
I am trying to return 2 numbers from my function to main(). They are both read in from an input file but it is not working out.
#include <fstream>
#include <iostream>
using namespace std;
ofstream outfile;
void heading(int);
int stuid(int,int);
[Code] ....
View 4 Replies
View Related
May 13, 2014
I am trying to realize a simple code with thread and lambda function.
My goal is to swap 2 variable . I launch 2 thread,
The first:
Put his value in a shared variable and notify it .
wait until an event on a condition variable occur.
read from shared value .
The second wait until an event on a condition variable occur.
Wake up
read from shared value .
Put his value in a shared variable and notify it.
This is the code
thread t1([&p1]()->void{
m.lock();
nt++;
if(nt==1) {
//first thread
unique_lock<mutex> u1(m); ***
[Code] .....
Why it say error "abort() has been called " on the istr ***
View 2 Replies
View Related
Mar 9, 2015
I need making my main function to run while not having any if or for statements. It can only declare variables and functions. Since my main function has command line arguments, how to so.
// This program counts all the words in a given file.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(int argc, char* argv[]) {
FILE* txtFile = NULL; // File Pointer
char str[1000000];
[Code] ....
View 5 Replies
View Related
Dec 4, 2014
How to how to make a function prototype that uses variables by reference. I'm making a decision based game where two running totals of two variables (ending and morality from decisions made) will decide the game outcome. I only have a few modules put in so far and most of the "story" parts cut down here to save space. I'm also getting an error saying there is more than one instance of overloaded function for the "whatToDo" module.
// ZombieGame.cpp : Defines the entry point for the console application.
//
#include <stdlib.h> /* srand, rand */
#include <time.h> /* time */
#include <iostream>
using namespace std;
//These are function prototypes to declare the functions being used
void WakeyWakey();
void TwentyMinsLater(int);
[Code] .....
View 2 Replies
View Related
Feb 3, 2015
I have the main() - which has entries like
Code:
main() {
int ss, ret, z;
float yy;
ret = function1(&yy, &ss, &z);
//int function1(flat *cc, int *dd, int *k) - is it correct?
[Code]...
View 5 Replies
View Related
Dec 14, 2014
I'm trying to implement Tarjan's Strongly Connected Components Algorithm in C++. Here's how I gotten so far:
void tarjan(vector<Vertex>& G){
index = 0;
while (!S.empty()) S.pop();
[Code]....
Here's an example graph for the algorithm to run: [URL]
Here's the first part of the output of the program: [URL]
all the index & lowlink values of the nodes are set to -1 in the beginning. global index value is set to 0. My problem is, the algorithm starts running on Vertex X-4. It runs the instruction X-4.index=0 & X-4.lowlink=0 then it calls itself with the paramater of node X-1. it sets X-1's index & lowlink values to 1. then it calls itself for X2. then it checks whether node X-4 has the index value <0 or not. Even though we set the value of X-4 to 0 in the first run, it still sees X-4.index as -1.
View 1 Replies
View Related
Mar 6, 2015
So I need to make a main function have no if/for/etc. statements so I need to move it to another function and call it in main. The problem is that it's a command line argument function so I'm confused on how it works. Here's an example:
Code:
#include <stdio.h>
int main(int argc, char* argv[])
{
printf("The program name %s", argv[0]);
if (argc == 2) {
printf("Argument supplied is %s", argv[1]); }
else if (argc > 2) {
printf("Too many arguments");}
else {
printf("One argument");}
}
How can i make this into two functions with main only declaring variables and calling other functions?
View 2 Replies
View Related
Aug 31, 2014
I had problem in comparing 2 char vairable in check function
if(room_no==r)
variable r take input from user and compare to room_no read from file.
#include<iostream>
#include<conio.h>
#include<fstream>
#include<stdio.h>
#include<dos.h>
#include<string>
#include<stdlib.h>
[Code] .....
View 2 Replies
View Related
Nov 6, 2014
I am putting a instance o the Vehicle Class inside the constructor of the Calculate Class then calling it later. I get a warning saying the variable is not used and a error when I try to used the functions from the vehicle class saying use of undeclared identifier.
Code:
#include <iostream>
#include "Calculate.h"
#include "Vehicle.h"
#include <fstream>
Calculate::Calculate(){
[Code] ....
View 9 Replies
View Related
Apr 4, 2013
Code:
if (IS_LEAP_YEAR(year))
const int days_per_month[] = {0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
else
const int days_per_month[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; Is it ok to declare the array in this manner or is it bad?
And i have to ask the user for a date to enter in my program. So should I use scanf or should I store the date in a string and then use sscanf. I have to check for valid input for everything like day, month, year etc. I did it as below..
Code:
int assignments;
assignments = scanf("%d / %d / %d", &month, &day, &year);
fflush(stdin);
if (assignments != 3)
{
printf("Retry: ");
}
else
error checking.
View 9 Replies
View Related
