I have (yet another) question about chars. Thanks to those who helped me with this before. I'm trying to do mainly 4 things at this point in the program. That is:
Build a 2D array 9x9 and fill it with underscores.
Ask for a row/column and then the number that the user wishes to go into that row/column as many times as the user wants.
Replace the specified blanks with the specified numbers.
Output the entire 9x9 char array on an ASCII art Sudoku board.
(Solving will come later.)
My problem is that when I enter the row/column and the number that I want to go into that row/column the dash that was originally in that spot disappears, but the number I entered does not appear in its place.
Here is the code so far:
#include <iostream>
#include <string>
#include <cstring>
using namespace std;
int main () {
//Builds 9x9 char array.
char dash[9][9];
for (int array=0; array<9; array++) {
for (int array2=0; array2<9; array2++) {
dash[array][array2]='_';
}
}
cout << "Input the row #, then the column #, then the number that you wish to fill that spot." << endl;
cout << "Remember that a Sudoku board is 9x9." << endl;
cout << "When you wish to finish input and solve, type all 0's and press enter." << endl;
int rowb;
char row[99];
int columnb;
char column[99];
int numb;
char num[99];
//Inputs the row/column and number to go into specified row/column.
int control=0;
while (rowb!=0){
control++;
cout << "Row: ";
cin >> rowb;
cout << "Column: ";
cin >> columnb;
cout << "Number: ";
cin >> numb;
row[control]=rowb-1;
column[control]=columnb-1;
num[control]=numb;
}
int length;
length=strlen(row);
//Replaces the _'s in the specified rows/columns and replaces them with the integer the user specified. This is where I think I'm having the problem.
for (control=0; control<length; control++) {
dash[row[control]][column[control]]=num[control];
}
//Builds the Sudoko board and outputs the full 9x9 array.
cout << "╔═══════════╦═══════════╦═══════════╗" << endl;
for (int count=0; count<3; count++) {
for (int count2=0; count2<3; count2++) {
cout << "║_" << dash[count][count2*3] << "_|_" << dash[count][count2*3+1] << "_|_" << dash[count][count2*3+2] << "_";
}
cout << "║" << endl;
}
cout << "╠═══════════╬═══════════╬═══════════╣" << endl;
for (int count=3; count<6; count++) {
for (int count2=0; count2<3; count2++) {
cout << "║_" << dash[count][count2*3] << "_|_" << dash[count][count2*3+1] << "_|_" << dash[count][count2*3+2] << "_";
}
cout << "║" << endl;
}
cout << "╠═══════════╬═══════════╬═══════════╣" << endl;
for (int count=6; count<9; count++) {
for (int count2=0; count2<3; count2++) {
cout << "║_" << dash[count][count2*3] << "_|_" << dash[count][count2*3+1] << "_|_" << dash[count][count2*3+2] << "_";
}
cout << "║" << endl;
}
cout << "╚═══════════╩═══════════╩═══════════╝" << endl;
return 0;
}
There is a problem assignment of the number entered in the loop.
//Replaces the _'s in the specified rows/columns and replaces them with the integer the user specified. This is where I think I'm having the problem.
for (control=0; control<length; control++) {
dash[row[control]][column[control]]=num[control]; //<<<--- Assignment issue.
}
You are assigning an integer value in a character array & thus when you display you will get the corresponding char for the ascii value & not the integer. Try changing the assignment as follows:
//Replaces the _'s in the specified rows/columns and replaces them with the integer the user specified. This is where I think I'm having the problem.
for (control=0; control<length; control++) {
dash[row[control]][column[control]]=num[control] + '0'; // Convert to ascii value of the integer, but will fail if not b/w 0 & 9.
}
Checking if the number entered in is between 1 & 9 is also advised if you choose to use the above observation.
Please add checks for the row & column entered as enter values which are not b/w 1 & 9 will lead to undefined behaviour due to accessing out of bound array elements if the values entered are not b/w 1 & 9.
Also as mentioned by Benjamin Lindley please update strlen code.
Hope this helps!
length=strlen(row);
This is undefined behavior, because row[0] was never initialized, and you never null terminate the string.
char row[99];
...
int control=0;
while (rowb!=0){
control++;
...
row[control]=rowb-1;
...
Notice that the first time through the loop, control is 1. So, you're setting the value of row[1], but not row[0]. Move the increment to the end of the loop. There may be some other problems, but this is the primary one responsible for the behavior you're seeing.
Also, for strlen to work, you need to null terminate the string.
And finally, you're making the same mistake you've made in this question and this question. Why aren't you seeming to get that? Chars display differently than ints. The following code will not display the number 1:
char c = 1;
std::cout << c;
Look at the answers to those other two questions.
Related
I am new to C++, learned it for more than a month. I have a beginner-level knowledge of Python, like creating a list, modifying it, loops, etc. I don't know some codes for C++ that I know in python.
I am making a program for a school class (creative program). This is a part of my code (description at the bottom):
int number, new_one, num_letter;
char one;
cout << "You chose to encypher a message\nPlease choose an integer between 1-25:";
cin >> number;
cout << "How many letters are in your word?";
cin >> num_letter;
if (num_letter == 1)
{
cout << "Enter the first letter";
cin >> one;
new_one = one + number;
cout << "Your encrypted message is '"
<< static_cast<char>(new_one)
<< "' with the code number of "
<< number;
I am making a program where it enciphers and deciphers a message. The user chooses the number of letters of their message (maximum of 10 because I don't know how to use a for-loop in C++ yet). Then, they choose an integer. Then, they enter the letter, hit Enter, enter the letter, and hit Enter for the number of letters in their message (I don't know how to separate strings to chars in C++ yet).
When the user enters their letter and hits Enter, I cin >> that letter into the variable one, which is a char. Then, I add that one to the number the user chose, so the ASCII code of the one increases by the value of the number.
For example, when I enter 3 for number and h for the value of one, 104 (the ASCII code of h) should add up with 3, resulting in 107, which I then would static_cast to a char value.
But, when I add h and 3, instead of creating 107, it creates 155. Same for other variables. I tried cout'ing static_cast<int>(one) (in this case, the letter h) and number (which is 3). They printed 104 and 3.
But, when I add those two values, it prints 155. Why is this happening?
This is my solution. Hope it helps!
#include <iostream>
using namespace std;
int main()
{
int offset = 0;
int num_with_offset;
int size;
// Gets offset from user
do{
cout << "You chose to encypher a message\nPlease choose an integer between 1-25: ";
cin >> offset;
} while (offset < 1 || offset > 25);
// Gets letters in word
do{
cout << "Letters in word: ";
cin >> size;
} while(size < 0);
// Given size, init arrays
int number[size];
char one[size];
// Conversion from char to int
for(int i = 0; i < (sizeof(one)/sizeof(one[0])); i++)
{
cout << "Enter character " << (i + 1) << ": ";
cin >> one[i];
num_with_offset = one[i] + offset;
// Converts ASCII to integer and stores it into array
number[i] = static_cast<int>(num_with_offset);
}
// Prints out the new encrypted message
for(int j = 0; j < (sizeof(number)/sizeof(number[0])); j++)
{
cout << "Your encrypted message is: "
<< number[j] << " , with the code number: "
<< offset << "." << endl;
}
cout << endl << endl;
return 0;
}
I'm new to C++ and i was trying to understand how to work with arrays. The idea I have is:
I wanted a user to input an array, the program to output the
array
Double all the values in the array and output that
And for each of the doubled values, add the digits of the doubled number
(1 digit number would remain the same), then output the new numbers as
well.
(e.g. if the array was [5, 6, 7, 8], the doubled values would be [10, 12, 14, 16] and then you would add each values digits like, [1+0, 1+2, 1+4, 1+6] to get [1, 3, 5, 7].
I put my code to show my progress, feel free to point out any errors along the way!
Any help is appreciated!
p.s. The nested loop didn't work :(
#include <iostream>
#include <string>
using namespace std;
int maxNum;
int num[20];
int main()
{
cout << "Enter an Array" << endl;
for (int i=0;i<20;i++)
{
cin >> num[i];
maxNum++;
if (num[i]==-1)
break;
}
cout <<"Your array is: " << endl;
for (int i=0;i<maxNum-1;i++)
cout << num[i];
cout << endl;
cout << "Your doubled array is:" << endl;
for (int j=0;j<maxNum-1;j++)
{
num[j]*=2;
cout << num[j];
}
cout << endl;
cout << "When the digits of each seat are added..." << endl;
for (int k=0;k<maxNum;k++)
{
for (int l=0;l<maxNum;l++)
{
int sum[20];
while (num[k]!=0)
{
sum[l]=sum[l]+num[k]%10;
num[k]=num[k]/10;
}
}
cout << sum[l];
}
cout << endl;
}
A few things:
maxNum and num[] are never initialized, it's dangerous.
that is not how you scan input. Ideally you woud do smth like while(cin >> tem_var){}. Or you could modify it to be if( !(cin >> num[i]) ) break;. That way you don't need to do maxNum-1 later too. (cin>>) will be True if it reads a variable succesfully and False otherwise. That way you can stop scanning by entering any non-number string, instead of running the loop for the rest of iterations, but leaving num[i] uninitialized if that happens.
you forget to output delimeters between array numbers which makes it hard to read.
cout << num[i] << "|"; or smth.
In the last part you make 3 loops: a k for loop that you never use, a l for loop to iterate num, and a k while loop to sum the digits. One of them is not necessary.
In the last part sum[] array, though filled correctly, is not outputted. You declare it inside the l loop, meaning it's deleted when you exit it. And even if you declared it outside. your cout << sum[l]; is outside the l loop, meaning it will only try to do the cout << sum[maxNum]; (the value of l the loop finishes with) while you only have [0:(maxNum-1)] elements in num and sum filled.
I'd suggest you try smth like for(k=1;k<num[l];k*=10) sum[l]+= num[l] / k % 10; instead of that while loop. It's shorter, gets the job done and leaves num[l] unchaged in case you decide to use it again afterwards.
You need to initialize sum array with all zeros first. You don't need nested loop.
Create a sum array to store the sum of each number and initialize it with 0's. First write a loop to traverse through the elements of the doubled array. For each element write a loop(you chose while loop) to traverse through the digits of each number and them to the corresponding sum element.
I've modified your code a little bit, go through it once.
#include <iostream>
#include <string>
using namespace std;
int maxNum;
int num[20];
int main()
{
cout << "Enter an Array" << endl;
for (int i=0;i<20;i++)
{
cin >> num[i];
maxNum++;
if (num[i]==-1)
break;
}
cout <<"Your array is: " << endl;
for (int i=0;i<maxNum-1;i++)
cout << num[i]<<' ';
cout << endl;
cout << "Your doubled array is:" << endl;
for (int j=0;j<maxNum-1;j++)
{
num[j]*=2;
cout << num[j]<<' ';
}
cout << endl;
cout << "When the digits of each seat are added..." << endl;
int sum[20];
for (int i=0;i<maxNum-1;i++)
sum[i]=0;
for (int k=0;k<maxNum-1;k++)
{
// for (int l=0;l<maxNum;l++)
// {
while (num[k]!=0)
{
sum[k]=sum[k]+num[k]%10;
num[k]=num[k]/10;
}
cout << sum[k]<<' ';
// }
}
cout << endl;
}
You don't need nested loop for that ,while making logic behind any program take a simple example and get the result,Don't jump directly to code. This will help you to building logics.
#include <iostream>
#include <string>
using namespace std;
int maxNum;
int num[20];
int main()
{
int sum=0;
cout << "Enter an Array" << endl;
for (int i=0;i<20;i++)
{
cin >> num[i];
maxNum++;
if (num[i]==-1)
break;
}
cout <<"Your array is: " << endl;
for (int i=0;i<maxNum;i++)
cout << num[i]<<ends;
cout << endl;
cout << "Your doubled array is:" << endl;
for (int j=0;j<maxNum;j++)
{
num[j]*=2;
cout << num[j]<<ends;
}
cout << endl;
cout << "When the digits of each seat are added..." << endl;
int r=0;
for (int k=0;k<maxNum;k++)
{
while (num[k]>0)
{
r=num[k]%10;
sum+=r;
num[k]=num[k]/10;
}
cout<<sum<<ends;
sum=0;
r=0;
}
cout << endl;
}
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I am new to C++ and have written some code in which I'm getting the following error:
Run-Time Check Failure #2 - Stack around the variable 'scores' was corrupted
What is causing this error?
Here is my code:
#include <iostream> // Enables cout and endl
#include <string>
#include <sstream>
#include "stdafx.h"
using namespace std;
int getInput();
int main()
{
int scores[5];
int i;
int j;
int numberOfScores;
for (i = 0; i < 6; i++) // Sets all 5 elements of the array to zero
{
scores[i] = 0;
}
cout << "How many scores do you have to enter?\n" << endl;
cin >> numberOfScores;
for (j = 0; j < numberOfScores; j++) // Gather test scores and increases each array index as that score is entered
{
scores[getInput()] ++;
}
cout << "The number of zeros: " << scores[0] << endl;
cout << "The number of ones: " << scores[1] << endl;
cout << "The number of twos: " << scores[2] << endl;
cout << "The number of threes: " << scores[3] << endl;
cout << "The number of fours: " << scores[4] << endl;
cout << "The number of fives: " << scores[5] << endl;
return 0;
}
int getInput()
{
int enteredScore;
cout << "Enter the test scores one at a time.\n";
cout << "The range of scores is 0 to 5.\n";
cin >> enteredScore;
if (enteredScore >= 0 && enteredScore <= 5)
{
return enteredScore;
}
else
{
cout << "Error! The range of scores is 0 to 5.\n";
cout << "Enter the test scores one at a time.\n";
cin >> enteredScore;
return enteredScore;
}
}
It seems that this declaration:
int scores[5];
Is incorrect. This creates an array with 5 numbers in it, indices from scores[0-4], however, you constantly refer to score[5], the sixth element of the array throughout your program. I recommend changing to
int scores[6];
The problem:
You are accessing your array out of bounds in several places.
Here you loop through 6 elements when you only have 5:
for (i = 0; i < 6; i++) // Loops through 6 elements
{
scores[i] = 0;
}
Here you call getInput() and use the return value as the index:
scores[getInput()] ++;
However, the first half of the function accepts inputs from the user in the range 0 to 5, thus allowing access to 6 elements:
if (enteredScore >= 0 && enteredScore <= 5)
It gets even worse if the user enters a number outside that range, as they are then given a second opportunity to enter a number, only this time there is no validation and any number they enter is accepted:
cin >> enteredScore;
return enteredScore;
Finally, you again attempt to access a 6th element here:
cout << "The number of fives: " << scores[5] << endl;
Solution:
First, you need to do one of two things:
Change the for loop, if statement, and cout statements so that they do not access index 5
or:
Create the array so that it has 6 elements: int scores[6];
Secondly, you need to fix the bug in your getInput() function so that it validates the input properly. You could try this for example:
int getInput()
{
int enteredScore;
cout << "Enter the test scores one at a time.\n";
cout << "The range of scores is 0 to 4.\n";
cin >> enteredScore;
while (enteredScore < 0 || enteredScore > 4)
{
cout << "Error! The range of scores is 0 to 4.\n";
cout << "Enter the test scores one at a time.\n";
cin >> enteredScore;
}
return enteredScore;
}
You have an error in
cout << "The number of fives: " << scores[5] << endl;
Your array is of size 5 but you are accessing the 6th element.
Same with for (i = 0; i < 6; i++) should be i < 5.
I do not get arrays, Im sure there are easier ways to make this program but I must do it the teacher's way and I am lost.
This is the assigment:
I do not get how I should go about these arrays. most confusing thing I seen by far.
What I would like is a guide or help on how i should program these arrays or how I should program arrays period. Not asking to do the rest for me, I already know how to do most of this, its just the arrays I like to know how to do.
This is my current program:
#include<iostream>
using namespace std;
void getPoints(int pPossible[], double pEarned[], int numItems, int limit);
int sumArray(double
void getpoints(int pPossible[], double pEarned[], int numItems, int limit)
{
int count;
while (limit == limit)
{
cout << "Input grade points for a category in the gradebook: " << endl
<< "How many items available in the category?: ";
cin >> numItems;
cout << endl;
if(numbItems > limit)
{
cout << "The Value exceeds the maximum number of items." << endl;
continue;
}
break;
}
count=1;
for(count=1; count<numItems; count++)
cout << "Enter points then points possible for Item " << count << ": ";
cin << pEarned[count] << pPossible[count];
return 0;
}
C++ array indexes are zero-based, so you should use zero for the initial value in the for loop. Also, you're missing the braces for the for loop body; as it is, it will run the cout line numItem-1 times and the cin line just once.
Another thing: the operators in the for's cin line should be >>, not <<. You want input here, not output.
Finally, like #ebyrob said, make numItems a reference parameter (it would be clearer for the caller to use a pointer instead, but the assignment asked for a reference parameter).
void getpoints(int pPossible[], double pEarned[], int& numItems, int limit)
{
//Read number of items
while (true)
{
cout << "Input grade points for a category in the gradebook: " << endl
<< "How many items available in the category?: ";
cin >> numItems;
cout << endl;
if(numItems >= limit)
{
cout << "The Value exceeds the maximum number of items." << endl;
continue;
}
break;
}
//Read earned and possible for each item
for(int count=0; count<numItems; count++)
{
cout << "Enter points then points possible for Item " << count << ": ";
cin >> pEarned[count] >> pPossible[count];
}
return 0;
}
I'm trying to get the user to input their name(s) using a while loop with an array and cin, but after the last person's name is input, the program crashes instead of moving on. Is there a way to fix this, or do I need to completely change up the code? I'm also fairly new to c++, so can any answers be given as simply as possible?
#include <iostream>
#include <string>
using namespace std;
int main()
{
unsigned int numberofplayers;
number://loop back here if more than 4 players
cout << "Number of players: ";
cin >> numberofplayers;
if(numberofplayers > 4 || numberofplayers < 1){
cout << "Invalid number, please enter a number from 1 to 4." << endl;
goto number;
}
string name[numberofplayers];
cout << "Enter your name" << endl;
int a = 1;
while(a < numberofplayers + 1){
cout << "Player " << a << ": ";
cin >> name[a];
cout << "Hello, " << name[a] << "." << endl;
a++;
}
}
You would probably facing array index out of bound, so Change you while loop to this and set a=0 to fill from 0th index.
while(a < numberofplayers){
}
Your last iteration exceeds the size of the array. You need to change it to
while(a < numberofplayers)
also, on another note, the keyword goto isn't used much anymore. I would suggest using a while there also like
while(true){
cout<<"number of players";
cin>>numberofplayers
if(numberofplayers is valid input){
break;
}
cout<<"bad input";
}
There is a question on stackoverflow discussing the use of goto extensively here:
GOTO still considered harmful?