so i have made this:
#include <iostream>
#include <string>
using namespace std;
int main()
{
while(true)
{
string x;
string y;
string an1[3] = {"quit","exit","leave"};
double ver = 0.1;
cout << "basic0.1% ";
cin >> x;
if (x == "upgrade")
{
system("yay -Syyu");
}
else if (x == "install")
{
cout << "What do you want to install?" << "\n";
cin >> y;
system(("sudo yay -S " + y).c_str());
}
else if (x == "version")
{
cout << "version: " << ver << "\n";
}
else if (x == "clear")
{
system("clear");
}
else if(x == "quit" || "leave" || "exit")
{
break;
}
else if(x == "ls")
{
}
}
return 0;
}
and in the else if(x == "ls"){} i wanted to show the output of the command,i tried putting system("ls");
but it just exits the program.
btw this should be a little terminal emulator for linux but i am not sure yet,i am just having some fun.
system("ls"). works fine. Your problem is this:
else if(x == "quit" || "leave" || "exit")
{
break;
}
Let's say you type ls. Then x contains the string "ls". x == "quit" is false because you didn't type quit. "leave" is true because it's a non-null pointer. "exit" is true because it's a non-null pointer. false || true || true is true, so the program quits.
Related
I'm doing a calculator in replit. Why does my cin.peek() == '\n' work when I enter + and - but it doesn't work when I enter *, /, or ^?
#include <iostream>
#include <math.h>
#include <vector>
#include <istream>
using namespace std;
float hasil;
vector<float> num;
vector<char> op;
void calc(float x, float y, char z) {
if (z == '+') {
hasil = x + y;
}
else if (z == '-') {
hasil = x - y;
}
else if (z == '*') {
hasil = x * y;
}
else if (z == '/') {
hasil = x / y;
}
else if (z == '^') {
hasil = pow(x,y);
}
else {
cout<< "wrong operator";
}
}
void input () {
float in;
char ch;
for (int i = 0;;i++) {
if(cin.peek() == '\n') {
break;
}
else if(cin.peek() == '+') {
op.push_back('+');
}
else if(cin.peek() == '-') {
op.push_back('+');
}
else if(cin.peek() == '*') {
op.push_back('*');
}
else if(cin.peek() == '/') {
op.push_back('/');
}
else if(cin.peek() == '^') {
op.push_back('^');
}
cin >> in;
num.push_back(in);
}
for (auto i = num.begin(); i != num.end(); ++i) {
cout << *i << " ";
}
for (auto i = op.begin(); i != op.end(); ++i) { //this is just so I can see what is in the vectors
cout << *i << " ";
}
calc(num.at(0),num.at(1),op.at(0));
for (int i = 2; i < num.size(); i++)
calc(hasil,num.at(i),op.at(i-1));
}
int main() {
cout << "rumus = ";
input();
cout << " = ";
cout << hasil;
}
When I enter 1+2+3+4 it works fine, but the for loop doesn't break when I, for example, enter 1/3 or 2/3.
if(cin.peek() == '\n') {
break;
}
Why doesn't this run when there is a /, *, or ^ in what I enter?
Sorry if I have bad grammar. English is not my first language, and I am very new to C++ and coding in general. I don't know much about coding.
If you enter "4-2", you might notice that the numbers are 4 and -2, and the operator is +.
It produces the correct result by mistake because of if(cin.peek() == '-') { op.push_back('+'). (Copy-paste bug?)
You never actually read an operator, you only read floats.
"+2" and "-2" are valid inputs when reading a number, and peek leaves the character in the stream.
Thus, "1+2" is read as "1" and "+2", "1-2" as "1" and "-2".
None of the other operators can prefix a number, so in all those cases the stream enters an error state, never reads anything, and you're stuck in a loop.
I will leave fixing the bug as an exercise.
This question already has answers here:
Why does std::getline() skip input after a formatted extraction?
(5 answers)
Closed 3 years ago.
I have written a C++ program to test compound inequalities/equalities.
When I run it in the IDE, it stops before it closes, but when I actually compile and run it as a executable, the console closes before I can read the output, even though I have specifically put a line at the end to pause it.
The code is included below:
#include <iostream>
using namespace std;
int main()
{
int x;
int y;
int a;
int b;
int test1;
int equality;
int test2;
bool et1;
bool lt1;
bool mt1;
bool et2;
bool lt2;
bool mt2;
bool t1;
bool t2;
cout << "What would you like to do? \n 1) Test two conditions are met \n 2) test if one condition is met out of two \n";
cin >> equality;
cout << "what would you like to test for the first pair of numbers? \n 1) if x == y \n 2) if x < y \n 3) if x > y \n";
cin >> test1;
cout << "what would you like to test for the second pair of numbers? \n 1) if x == y \n 2) if x < y \n 3) if x > y \n";
cin >> test2;
cout << "Choose the first number to the first inequality/equality \n";
cin >> x;
cout << "Choose the second number to the first inequality/equality \n";
cin >> y;
cout << "Choose the first number to the second inequality/equality \n";
cin >> a;
cout << "Choose the second number to the second inequality/equality \n";
cin >> b;
if (test1 == 1 && x == y){
et1 = true;
}
else if (test1 == 2 && x < y) {
lt1 = true;
}
else if (test1 == 3 && x > y) {
mt1 = true;
}
else if (test2 == 1 && a == b) {
et2 = true;
}
else if (test2 == 2 && a < b) {
lt2 = true;
}
else if (test2 == 3 && a > b) {
mt2 = true;
}
if (lt1 == true || et1 == true || mt1 == true) {
t1 = true;
}
if (lt2 == true || et2 == true || mt2 == true) {
t2 = true;
}
if (equality = 1 && t1 == true && t2 == true) {
cout << "this compound and inequality is true";
}
else if (equality = 2 ) {
if (t1 == true || t2 == true) {
cout << "this compound or inequality is true";
}
cout << "this compound inequality is true";
}
std::cin.get();
return 0;
}
You can include the header file "conio.h" and do a getch() call whenever you want a pause in your program
#include<iostream>
#include<conio.h>
using namespace std;
int main()
{
cout<<"After printing this there will be a pause.Press any character to contine\n";
getch();
cout<<"Code ends\n";
return(0);
}
I am capturing video from my webcam and if the user hits the Enter key I take a picture. Then I ask "Is the picture okay?" to user and wait for an input. If he says "No", I keep doing the same thing, until he says "Yes".
But if he says "No", and in the meantime I type something in the terminal, getline() function writes whatever I type into its buffer, and when I ask the question again it goes directly to "invalid input" state.
How do I prevent this?
I have read a lot of questions regarding this and I tried to use cin.ignore() and cin.clear() before/after after I call getline(), but they didn't help.
// Do capturing here
string choice;
int choiceIsOkay = 0;
while (choiceIsOkay == 0)
{
cout << "Is the picture okay? (Y/N): ";
getline(cin, choice);
if ((choice == "Y") || (choice == "y"))
{
choiceIsOkay = 2;
}
else if ((choice == "N") || (choice == "n"))
{
choiceIsOkay = 1;
}
else
{
cout << "\nInvalid input\n";
choiceIsOkay = 0;
}
}
if (choiceIsOkay == 2)
{
runAlgorithm = 1;
break;
}
else choiceIsOkay = 0;
If I understand your issue, if user enters Some Random Text In, your program always jump in "Invalid input" and never stops to wait for users input. Following code should resolve your issue.
#include <iostream>
#include <string>
using namespace std;
int main()
{
int runAlgorithm;
// Do capturing here
int i = 0;
while (i++ < 3)
{
int choiceIsOkay = 0;
string choice;
while (choiceIsOkay == 0)
{
cout << "Is the picture okay? (Y/N): ";
getline(cin, choice);
if ((choice == "Y") || (choice == "y"))
{
choiceIsOkay = 2;
}
else if ((choice == "N") || (choice == "n"))
{
choiceIsOkay = 1;
}
else
{
cout << "nInvalid inputn";
choiceIsOkay = 0;
}
// Ignore to the end of line
cin.clear();
}
}
return 0;
}
I am writing a taste test program for a class and it will run fine up until my if statements. However, once I get into my if statements it isn't incrementing i, so it never leaves the while loop.
#include <iostream>
using namespace std;
void main()
{
int i = 0;
int q = 0;
int p = 0;
int c = 0;
char preference;
int x = 0;
cout << "How many taste tests would you like to do?" << endl;
cin >> x;
while (i<x)
{
cout << "Do you prefer Coke, Pepsi, or are they the same? Use c for coke, p for pepsi, and q for the same\n";
cin >> preference;
if (preference == 'q' || preference == 'Q')
{
q = q + 1;
i++;
}
if (preference == 'p' || preference == 'P')
{
p = p + 1;
i++;
}
if (preference == 'c' || preference == 'C')
{
c = c + 1;
i++;
}
}
if (p>q)
{
cout << "Pepsi wins" << endl;
if (c>p)
cout << "Coke wins" << endl;
if (c == p)
cout << "Tie" << endl;
}
}
I think that you are trying to check if the a determined char was clicked by cin >> preference but you are test int vars, so if i press 'q'
//if(preference==q || preference==Q) // 'q'==0 || 'p'==0
if(preference=='q' || preference=='Q') // 'q'=='q' || 'q'=='Q'
so add ''
I hope this helps
Change the following lines in the code for the expected behavior.
//if(preference==q || preference==Q)
if(preference=='q' || preference=='Q'
//if(preference==p || preference==P)
if(preference=='p' || preference=='P')
//if(preference==c || preference==C)
if(preference=='c' || preference=='C')
I have a function to return a bool:
bool restart()
{
std::string answer;
bool answered = false;
while(answered == false)
{
cout << endl << endl << "Do you want to play again? y/n : ";
cin >> answer;
if(answer == "y" || answer == "Y" || answer == "1" || answer == "yes")
{return true;}
if(answer == "n" || answer == "N" || answer == "0" || answer == "no")
{return false;}
}
}
When I call it using:
cout << restart();
I get the output:
Do you want to play again? y/n : y
56
Can anyone see how to fix this strange problem?
Thanks in advance.
My WIP code as it is now:
#include <iostream>
#include <cstdlib>
using namespace std;
void drawScreen(int grid[3][3]); //
int movef(int grid[3][3], bool playersMove);
int updateGrid(int grid[3][3], int move, bool playersMove);
bool hasWon(int grid[3][3]);
bool swapMover(bool playersMove); //
bool restart();
void endGame();
int main()
{
int grid[3][3] = {{1,2,3},{4,5,6},{7,8,9}};
bool appRunning = true, gameRunning = true, playersMove = true;
int move;
// tests //
std::cout << restart();
// tests //
//while(appRunning == true)
//{
// while(gameRunning == true)
// {
// drawScreen(grid);
// move = movef(grid, playersMove);
// grid[3][3] = updateGrid(grid, move, playersMove);
// drawScreen(grid);
// gameRunning = hasWon(grid);
// playersMove = swapMover(playersMove);
// }
// appRunning = restart();
//}
//endGame();
}
void drawScreen(int grid[3][3])
{
for(int i = 0; i < 3; i++)
{
for(int j = 0; j < 3; j++)
{
if(grid[i][j] == 10){cout << "X ";if(j == 2){cout << endl << endl;}}
if(grid[i][j] == 11){cout << "O ";if(j == 2){cout << endl << endl;}}
if(grid[i][j] != 10 && grid[i][j] != 11){cout << grid[i][j] << " ";
if(j == 2){cout << endl << endl;}}
}
}
}
int movef(int grid[3][3], bool playersMove)
{
return 0;
}
int updateGrid(int grid[3][3], int move, bool playersMove)
{
return 0;
}
bool hasWon(int grid[3][3])
{
return false;
}
bool swapMover(bool playersMove)
{
if(playersMove == true){return false;}
if(playersMove == false){return true;}
}
bool restart()
{
std::string answer;
bool answered = false;
while(answered == false)
{
cout << endl << endl << "Do you want to play again? y/n : ";
cin >> answer;
if(answer == "y" || answer == "Y" || answer == "1" || answer == "yes")
{return true;}
if(answer == "n" || answer == "N" || answer == "0" || answer == "no")
{return false;}
}
}
void endGame()
{
}
[This is somewhat of a repost of my comment since OP said it solved his problem]
You have no return value defined outside of the while loop. If somehow you get outside of it, you do not return a value (though I have no idea what behavior is expected or even if any behavior is expected in this case)
To make my answer a bit more thorough, I have found this:
Why does flowing off the end of a non-void function without returning a value not produce a compiler error?
OK, I'm making a guess. Your original code has the line
grid[3][3] = updateGrid(grid, move, playersMove);
And your grid definition is
int grid[3][3] = {{1,2,3},{4,5,6},{7,8,9}};
This means that your are writing out of the array bounds. This is undefined behavior.
Please correct this and check if your program works as expected.
I used the mingw32 compiler, when using g++ 4.8 it works fine. It seems to be a compiler error. (thanks to grizzly)