I want to print out some values from 2-d array C++ - c++

I want to input data from txt file.
the file contains 2-d array [5][5]
how can i print out the any value i want?
i don't want to print out the whole 5*5 data
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main()
{
double distance[5][5] ;
string line;
ifstream ratefile;
ratefile.open("a.txt");
ofstream file;
if (ratefile.is_open())
{
while (! ratefile.eof() )
{
getline (ratefile,line);
ratefile.getline(distance, 25, '*');
cout << "\nDistance [0][0]" << ": " << distance[0][0];
cout << "\nDistance [0][1]" << ": " << distance[0][1];
cout << "\nDistance [0][2]" << ": " << distance[0][2];
cout << "\nDistance [0][3]" << ": " << distance[0][3];
cout << "\nDistance [1][0]" << ": " << distance[1][0];
cout << "\nDistance [1][1]" << ": " << distance[1][1];
cout << "\nDistance [1][2]" << ": " << distance[1][2];
cout << "\nDistance [1][3]" << ": " << distance[1][3];
cout << endl;
cin.get();
return 0;
}

If you only want to output one value and the user should be able to choose a value, you can do something like this:
int x, y;
cin >> x;
cin >> y;
cout << "\nDistance [" << x << "][" << y << "]" << ": " << distance[x][y];
But you should check if the user enter valid numbers (0 <= x < 4 and 0 <= y < 4)

There is part of the code missing, but you are printing values you want. Simply remove the lines you don't want to print.
Of course you can also use variables:
int x = 2,y = 2;
cout << endl << "Distance [" << x << "][" << y << "] : " << distance[x][y];

Related

Wrong values after first cout

I'm making a test program for starting with C++ :)
It's showing wrong values after first print
This is the code (very simple)
#include "pch.h"
#include <iostream>
#include <Windows.h>
using namespace std;
int main()
{
int varInt = 123456;
char varString[] = "DefaultString";
char arrChar[128] = "Long char array right there ->";
int * ptr2int;
ptr2int = &varInt;
int ** ptr2ptr;
ptr2ptr = &ptr2int;
int *** ptr2ptr2;
ptr2ptr2 = &ptr2ptr;
while(1){
cout << "Process ID: " << GetCurrentProcessId() << endl;
cout << "varInt (0x" << &varInt << ") = " << varInt << endl;
cout << "varString (0x" << &varString << ") = " << varString << endl;
cout << "varChar (0x" << &arrChar << ") = " << arrChar << endl;
cout << "ptr2int (0x" << hex << &ptr2int << ") = " << ptr2int << endl;
cout << "ptr2ptr (0x" << hex << &ptr2ptr << ") = " << ptr2ptr << endl;
cout << "ptr2ptr2 (0x" << hex << &ptr2ptr2 << ") = " << ptr2ptr2 << endl;
cout << "Press ENTER to print again." << endl;
getchar();
cout << "-----------------------------------" << endl;
}
return 0;
}
The expected results are obvious, as the code is published as is:
Process ID is integer so should return 12704 (or any int value) instead of 31a0
varInt it's also integer and should return 123456 instead of 1e240
1e240 is the same thing as 123456 in hex. The first iteration will print 123456 correctly but after you set the base flag of cout to hex mode, you need to set it back to dec to print 123456 again on the next loop.
cout << "varInt (0x" << &varInt << ") = " << dec << varInt << endl;
See here for documentation.

Creating a Simple Calculator, having an issue with the addition

I'm trying to create a simple calculator and i already encountered an issue when addition is being used. I created a function for addition and whenever i pass in two values i get a different answer. For Example when i add 4,5 i would expect to get 9 but the answer i get is 0029144C . Im still a beginner, so at first i wasn't sure if using type bool for the adding function would affect my result, but i changed it to type float and still getting the same result (in case anyone asks).
#include "stdafx.h"
#include <iostream>
#include <string>
using namespace std;
void SimCalcMenu();
void additionSign();
bool makeSum(float num1, float num2);
int main() {
float firstNum, SecondNum;
char operationLetter;
SimCalcMenu();
cout << " Please Select an Operation You Would Like to Perform ";
cin >> operationLetter;
if (operationLetter == 'a' || operationLetter == 'A')
{
additionSign();
cout << " Enter the First Number : ";
cin >> firstNum;
cout << " Enter the Second Number: ";
cin >> SecondNum;
makeSum(firstNum, SecondNum);
cout << " The Sum of " << firstNum << " and " << SecondNum << " is :" << makeSum << endl;
}
else
{
cout << " Error ";
}
return 0;
}
void SimCalcMenu() {
cout << "------------------------------------------------------------------------------" << endl;
cout << " WELCOME TO SIM CALCULATOR " << endl;
cout << "------------------------------------------------------------------------------" << endl;
cout << endl;
cout << " Please Select an Operation : " << endl;
cout << " A.) Addition " << endl;
cout << " B.) Subtraction " << endl;
cout << " C.) Multiplication " << endl;
cout << " D.) Division " << endl;
cout << " E.) Roots ( Only Positive Number)" << endl;
cout << " F.) Power ( Only Positive Number " << endl;
cout << " G.) Percentage " << endl;
cout << " H.) Display functions execution " << endl;
cout << " I.) Quit " << endl;
cout << "------------------------------------------------------------------------------" << endl;
}
void additionSign() {
cout << "------------------------------------------------------------------------------" << endl;
cout << " ADDITION " << endl;
cout << "------------------------------------------------------------------------------" << endl;
}
bool makeSum(float num1, float num2) {
float totSum;
totSum = num1 + num2;
return totSum;
}
makeSum() should return float, because you are returning the sum of two floats.
You are not getting the right result because you are printing makeSum, which is the address of the function. You want to print the value of makeSum(firstNum, SecondNum).
this line
cout << " The Sum of " << firstNum << " and " << SecondNum << " is :" << makeSum << endl;
IS 'printing' 'makesum', makesum is a function so its printing the address of makesum
you need
cout << " The Sum of " << firstNum << " and " << SecondNum << " is :" << makeSum(firstNum, SecondNum) << endl;
now at least it will print the result of makesum. As other have pointerd out that function is wrong (it returns a bool).
should be
float makeSum(float num1, float num2) {
float totSum;
totSum = num1 + num2;
return totSum;
}

C++ Program need help to debug

#include <iostream>
#include <fstream>
#include <iomanip>
#include <stdlib.h>
using namespace std;
struct football_game
{
string visit_team;
int home_score;
int visit_score;
};
void printMenu();
int main()
{
int i, totalValues = 0;
ifstream inputFile;
string temp = "";
inputFile.open("games.txt");
if (!inputFile)
{
cout << "Error opening Input file!" << endl;
exit(101);
}
inputFile >> totalValues;
getline(inputFile, temp);
cout << " *** Football Game Scores *** " << endl << endl;
cout << " * Total Number of teams : " << totalValues << endl << endl;
football_game* records = new football_game[totalValues];
// while (!inputFile.eof())
// {// == NULL) {
for (i = 0; i < totalValues; i++)
{
getline(inputFile, records[i].visit_team);
cout << records[i].visit_team << endl;
inputFile >> records[i].home_score >> records[i].visit_score;
cout << records[i].home_score << " " << records[i].visit_score << endl;
getline(inputFile, temp);
}
//}
cout << endl;
int choice = 0;
int avg_home_Score = 0;
int avg_visit_Score = 0;
printMenu(); // prints menu
cout << "Please Enter a choice from the Menu : ";
cin >> choice;
cout << endl << endl;
while (true)
{
switch (choice)
{
case 1:
cout << " Score Table " << endl;
cout << " ***********************" << endl << endl;
cout << " VISIT_TEAM"
<< " "
<< " HIGH_SCORE"
<< " "
<< "VISIT_SCORE " << endl;
cout << " -----------"
<< " "
<< "-----------"
<< " "
<< "------------" << endl;
for (int i = 0; i < totalValues; i++)
{
cout << '|' << setw(18) << left << records[i].visit_team << " " << '|'
<< setw(7) << right << records[i].home_score << " " << '|' << setw(7)
<< right << records[i].visit_score << " " << '|' << endl;
}
cout << endl << endl << endl;
break;
case 2:
{
string team_name;
cout << "Enter the Team Name : ";
cin >> team_name;
for (int i = 0; i < totalValues; i++)
{
if (records[i].visit_team == team_name)
{
cout << " VISIT_TEAM"
<< " "
<< " HIGH_SCORE"
<< " "
<< "VISIT_SCORE " << endl;
cout << " -----------"
<< " "
<< "-----------"
<< " "
<< "------------" << endl;
cout << '|' << setw(18) << left << records[i].visit_team << " " << '|'
<< setw(7) << right << records[i].home_score << " " << '|'
<< setw(7) << right << records[i].visit_score << " " << '|'
<< endl;
}
}
cout << endl;
break;
}
case 3:
{
for (int i = 0; i < totalValues; i++)
avg_home_Score += records[i].home_score;
cout << "Average home_score: " << (avg_home_Score / totalValues) << endl << endl;
break;
}
case 4:
{
for (int i = 0; i < totalValues; i++)
avg_visit_Score += records[i].visit_score;
cout << "Average visit_score: " << (avg_visit_Score / totalValues) << endl << endl;
break;
}
default:
{
cout << "Please enter valid input !!" << endl;
break;
}
}
printMenu();
cin >> choice;
}
return 0;
}
void printMenu()
{
cout << " Menu Options " << endl;
cout << " ================ " << endl;
cout << " 1. Print Information of all Games[Table Form] " << endl;
cout << " 2. Print Information of a Specific Game " << endl;
cout << " 3. Print Average points scored by the Home Team during season" << endl;
cout << " 4. Print Average points scored against the Home Team" << endl << endl << endl;
}
Here is the input file i am using
games.txt
5
SD Mines
21 17
Northern State
10 3
BYU
10 21
Creighton
14 7
Sam Houston State
14 24
When i am using the 2nd option (Print Information of a Specific Game) from the output screen,
it ask me to enter the team name and when i enter the team-name.
For example: SD Mines it gives me an error, but when I enter the team-name with no space like: BYU it works fine for me.
cin >> team_name;
Takes the input only upto space.
You might want to use cin.getline() for taking space separated strings as input.
A small program demonstrating the same :
#include <iostream>
#include <string>
int main ()
{
std::string name;
std::cout << "Please, enter your full name: ";
std::getline (std::cin,name);
std::cout << "Name is : , " << name << "!\n";
return 0;
}
std::cin ignores whitespaces by default.
To include spaces in your input try :
getline(cin, team_name);
This would pick up all the characters in a line until you press enter. This is available in
#include<string>
You need to flush the std::cin buffer after reading the choice:
#include <limits>
//...
cin >> choice;
cin.clear();
cin.ignore(numeric_limits<streamsize>::max(), '\n');
Refer to this question for detailed explanation.
Also, if you want to read strings with spaces from the standard input, replace this:
cin >> team_name;
with this:
getline(cin, team_name);
as already mentioned in other answers. No need to flush std::cin this time, since you have already read the full line.
Finally, remove extra newlines from your games.txt:
5
SD Mines
21 17
Northern State
...

Must have pointer to object type c++ (Array)

I have a pointer to object error type for the variable "carrierTime" i have created. If i make this an array, carrierTime becomes an error in the first if statement, however if i leave it without any array i get an error on the last line of the code where i have used carrierTime in a multiplication.
can anyone help??
platform used:visual studios
#include "AMcore.h"
#include <iostream>
#include <iomanip>
#include <fstream>
#include <string>
using namespace std;
int main()
{
cout << "Amplitude Modulation Coursework" << endl;
cout << "Name: Mohammad Faizan Shah" << endl;
cout << "Student ID: 5526734 \n\n\n" << endl;
std::ifstream file,file2;
string filename1,filename2;
int rowCounter = 0;
double informationTime;
double informationAmplitudeAmount[361];
long double carrierTime;
double carrierAmplitudeAmount[361];
double totalAmplitudeAmount[1000];
int plotPoint;
cout << "Please enter the filename of the Carrier wave \n" << endl;
cin >> filename1;
file.open("carrier.txt");
if (file.is_open())
{
file >> carrierTime;
while (!file.fail())
{
cout << "row" << setw(3) << rowCounter;
cout << " Time = " << setw(5) << carrierTime;
file >> carrierAmplitudeAmount[rowCounter];
rowCounter++;
if (!file.fail())
{
cout << " Carrier signal= " << setw(5) << carrierAmplitudeAmount;
file >> carrierTime;
}
cout << endl;
}
if (file.eof())
cout << "Reached the end of file marker" << endl;
else
cout << "Error whilst reading input file" << endl;
}
else
{
cout << "Error opening input file, ";
cout << "check carrier.txt exists in the current directory." << endl;
}
file.close();
cout << "\n\n" << endl;
cout << "Please enter the filename of the information wave \n\n\n" << endl;
cin >> filename2;
file2.open("information.txt");
if (file2.is_open())
{
file2 >> informationTime;
while (!file2.fail())
{
cout << "row" << setw(3) << rowCounter;
cout << " Time = " << setw(5) << informationTime;
file2 >> informationAmplitudeAmount[361];
rowCounter++;
if (!file2.fail())
{
cout << " Carrier signal= " << setw(5) << informationAmplitudeAmount;
file2 >> informationTime;
}
cout << endl;
}
if (file2.eof())
cout << "Reached the end of file marker" << endl;
else
cout << "Error whilst reading input file" << endl;
}
else
{
cout << "Error opening input file, ";
cout << "check carrier.txt exists in the current directory." << endl;
}
file.close();
cout << "Reading from txt file has completed" << endl << endl;
cout << "\n\n" << endl;
cout << "\n\n" << endl;
cout << "please enter number of sample points to plot:| \n" << endl;
do{
cin >> plotPoint;
if (plotPoint <= 361)
{
cout << "\n plotting the graph.\n" << endl;
}
else if (plotPoint > 361)
{
cout << "Value is too high.. Try value lower than 361\n" << endl;
}
} while (plotPoint > 361);
cout << "row" << setw(3) << rowCounter;
file >> carrierAmplitudeAmount[361];
rowCounter++;
plotPoint = 361 / plotPoint;
cout << " Time \| Amplitude Modulation plot\n------------+--------------------------------------------------\n";
totalAmplitudeAmount[0] = carrierAmplitudeAmount[0] * informationAmplitudeAmount[0];
cout << setw(6) << carrierTime << setw(4) << "\|" << setw(48) << "*" << totalAmplitudeAmount[0] << endl;
for (int i = 1; i <= 361; i = i + plotPoint) {
totalAmplitudeAmount[i] = informationAmplitudeAmount[i] * carrierAmplitudeAmount[i];
int y = totalAmplitudeAmount[i] * 22;
cout << setw(6) << carrierTime[i++] << setw(4) << "\|" << setw(26 + y) << "*" << totalAmplitudeAmount[i] << endl;
}
cout << "End of program" << endl;
system("pause");
return 0;
}
cout << setw(6) << carrierTime[i++] << setw(4) << "\|" << setw(26 + y) << "*" << totalAmplitudeAmount[i] << endl;
carrierTime[i++] does not look correct. The variable is not defined as a pointer.
Also, proper debugging would help you catch these errors for yourself.

xcode "expected unqualified-id" on cout

I'm trying to make a program to calculate the y component of a user-input number for 7 different aspect ratios. This is probably a simple problem somewhere in the declarations at the top, but I have very little experience with c++. I am writing in xcode. Thanks!
I'm getting the following error messages:
19:13: Invalid operands to binary expression ('std::__1::basic_istream' and '')
32:6: Expected unqualified-id
//
// aspect1.cpp
// aspectRatioCalculator
//
#include <iostream>
using namespace std;
int main()
{
int a;
cout << "Enter a number to calculate its complements at multiple aspect ratios." << endl;
cin>> a >> endl;
int b = (a*9)/17;
int c = (a*9)/16;
int d = (a*5)/8;
int e = (a*4)/5;
int f = (a*3)/5;
int g = (a*3)/4;
int h = (a*2)/3;
cout << "17:9 | " << a << ":" << b << endl;
cout << "16:9 | " << a << ":" << c << endl;
cout << " 8:5 | " << a << ":" << d << endl;
cout << " 5:4 | " << a << ":" << e << endl;
cout << " 5:3 | " << a << ":" << f << endl;
cout << " 4:3 | " << a << ":" << g << endl;
cout << " 3:2 | " << a << ":" << h << endl;
}
std::endl is an output manipulator. It isn't meant to be used with input streams (which are used for input). Change this: cin >> a >> endl; to cin >> a; cout << endl;.