Basically, this program allows a user to enter a sentence and depending on the users selection, it will show the middle character of the sentence, display it uppercase or lowercase, or backwards. Simple program, but I am new to programming so that may be the problem. I would like to figure out how to use loops instead of a ton of if statements. When I try to make some loops it breaks certain parts of the code but I am sure that is because I don't properly understand them. If you have any criticism or any advice on the code, I'd be happy to hear it. Thanks in advance!
#include "stdafx.h"
#include <iostream>
#include <string>
using namespace std;
int main()
{
int sel;
string sent;
bool validinput;
int i;
int x;
int j;
int a;
cout << "Welcome to my program. Enter a sentence and select one of the options below.\n";
cout << "Enter -999 to exit the program." << endl;
cout << "============================================================================" << endl;
cout << endl;
cout << "1. Display the middle character if there is one." << endl;
cout << "2. Convert to uppercase." << endl;
cout << "3. Convert to lowercase." << endl;
cout << "4. Display backwards." << endl;
cout << "Enter a sentence: ";
getline (cin, sent);
cout << "Selection: ";
cin >> sel;
if (sel < 1 && sel > 4)
{
cout << "Invalid input. Try again. Selection: ";
cin >> sel;
validinput = false;
}
else (sel >= 1 && sel <= 4);
{
validinput = true;
}
if (validinput == true)
{
if (sel == 1)
{
j = sent.length() / 2;
cout << "The middle character is: " << sent.at(j) << endl;
}
if (sel == 2)
{
for (int i = 0; i < sent.length(); i++)
{
if (sent.at(i) >= 'a' && sent.at(i) <= 'z')
{
sent.at(i) = sent.at(i) - 'a' + 'A';
}
}
cout << "Uppercase: " << sent << endl;
}
if (sel == 3)
{
for (int x = 0; x < sent.length(); x++)
{
if (sent.at(x) >= 'A' && sent.at(x) <= 'Z')
{
sent.at(x) = sent.at(x) - 'A' + 'a';
}
}
cout << "Lowercase: " << sent << endl;
}
if (sel == 4)
{
for (a = sent.length() - 1; a >= 0; a--)
{
cout << sent.at(a);
}
}
}
system("pause");
return 0;
}
Personally I would use the switch selection statement. I roughly did this just to explain a bit on how it can make your code more friendly and understandable.
int sel;
bool validInput = false;
switch(sel)
{
case 1:
//display middle char if there's one
case 2:
//convert to uppercase
case 3:
//convert to lowercase
case 4:
//display backwards
validInput = true;
break;
default: //if number does not meat 1, 2, 3 or 4
validInput = false;
break;
}
As you may notice, for case 1, case 2, case 3 and case 4, there's a break just to say that if the number is between 1 to 4; validInput is true.
Reference: Switch Selection Statement
i suggest using a switch. It will organize your code better. From looking at your code you seem to have used for and if wisely. But I suggest the if statements checking for the input be replaced with switch.
Related
I'm making a calculator program but I already encounter a problem. Well, my code is in a loop that will call a function to display the choices and then ask the user to pick, a/s/m/d are the choices. If the input is on the choices, it will proceed to the next step. Otherwise, it will loop and then call the function again.
#include <iostream>
using namespace std;
void home()
{
cout << "\nChoose your operation:" << endl;
cout << "\tType [A] for Addition" << endl;
cout << "\tType [S] for Subtraction"<< endl;
cout << "\tType [M] for Multiplication" << endl;
cout << "\tType [D] for Division" << endl;
}
int main()
{
char operation;
bool no_operator = true;
int design = 73;
for (int i = 0; i < design; i++){
if (i == 25){
cout << " WELCOME TO CALCULATOR ";
i += 22;
}
else i == 72 ? cout << "*\n" : cout << "*";
}
while (no_operator){
home();
cout << "\nOperation: ";
cin >> operation;
if (operation == 'A' || operation == 'a')
{
cout << "\nIt will going to add numbers";
no_operator = false;
}
else if (operation == 'S' || operation == 's')
{
no_operator = false;
cout << "\nIt will going to subtract numbers";
}
else if (operation == 'M' || operation == 'm')
{
no_operator = false;
cout << "\nIt will going to multiply numbers";
}
else if (operation == 'D' || operation == 'd')
{
no_operator = false;
cout << "\nIt will going to divide numbers";
}
else
{
cout << "\tInvalid Input: You must enter A/S/M/D only\n";
//home();
}
}
return 0;
}
My problem is it will run the '''home()''' in else statement even if the input is correct on the second loop.
I want to stop the '''home()''' to be called when the input is correct
Your code works perfectly fine. Make sure you're inputting the correct letters.
Also for this code, a "do while()" loop would be better.
You program is working perfectly fine as the input is correct it does not show the home rather print the message it will going to divide etc.
I'm new to C++. I have errors. But, i dont know how to fix it. Could anyone please help me? Thank you.
P - Print numbers
A - Add a number
M - Display mean of the numbers
S - Display the smallest number
L - Display the largest number
Q - Quit
Errors : expected unqualified id before return 0
error : expected ';' before {}
#include <iostream>
#include <vector>
using namespace std;
int main(){
char input {};
vector <double> numbers {};
int number{};
int sum{};
int min_number{};
int max_number{};
bool condition {true};
cout << "Enter a command" << endl;
cin >> input;
if(numbers.size() > 0){
while(condition){
if (input == 'P' || input == 'p'){
for(auto x: numbers)
cout << x << endl;
}
else if(input == 'A' || input == 'a'){
cout << "Enter a number";
cin >> number;
numbers.push_back(number);
}
else if(input == 'M' || input == 'm'){
for(auto x : numbers)
sum += x;
cout << sum / numbers.size() << endl;
}
else if(input =='S' || input == 's'){
for(size_t i {0}; i < numbers.size(); ++i)
if(numbers.at(i) < min_number)
min_number =numbers.at(i);
}
else if(input =='L' || input == 'l'){
for(size_t i {0}; i < numbers.size(); ++i)
if(numbers.at(i) > max_number)
max_number =numbers.at(i);
}
else if(input =='Q' || input == 'q'){
condition {false};
}
}
cout << "[] - list is empty, unable to calculate" << endl;
}
return 0;
}
In your section dealing with Q/q, the statement:
condition {false};
is not a valid form of assignment, you should instead use:
condition = false;
The braces are fine for initialisation, but that's not what you're trying to do on that line.
As an aside, this line:
if(numbers.size() > 0){
seems a little strange. Since you initialise the list to empty, the main loop will never start (because it's inside the if block) even though you have already asked the user for input.
That's a runtime error rather than a syntax error but you'll still need to fix it at some point.
I suspect that particular should should be done only as part of the calculation of the mean, so as to avoid dividing by zero.
I have written this for you. Since, you're a learner, I think that you should be practicing better things like STL functions and not using using namespace std; at top.
You may find some things new, but don't be frightened, just search them on some website like cppreference and see what that entity do and how to effectively use it.
There were many logical errors. #paxdiablo has mentioned them in his answer. I have removed every of them and this code works.
#include <algorithm>
#include <cctype>
#include <iostream>
#include <vector>
int main() {
std::vector<double> numbers;
while (true) {
char input;
std::cout << "Enter a command: ";
std::cin >> input;
switch (std::toupper(input)) {
case 'P':
if (numbers.empty())
std::cerr << "The list is empty!" << std::endl;
else {
for (auto &&i : numbers)
std::cout << i << ' ';
std::cout << std::endl;
}
break;
case 'A': {
int number;
std::cout << "Enter a number: ";
std::cin >> number;
numbers.push_back(number);
break;
}
case 'M':
if (numbers.empty())
std::cerr << "The list is empty! Cannot perform the operation!!";
else {
int sum = 0;
for (auto &&i : numbers)
sum += i;
std::cout << "Mean: " << (sum / numbers.size()) << std::endl;
}
break;
case 'S':
std::cout << "Smallest Number: " << *std::min_element(numbers.begin(), numbers.end()) << std::endl;
break;
case 'L':
std::cout << "Largest Number: " << *std::max_element(numbers.begin(), numbers.end()) << std::endl;
break;
case 'Q':
return 0;
default:
std::cerr << "Unrecognised Command!!" << std::endl;
}
}
return 0;
}
I'm trying to get the program to loop again, up to three times, if the user entered a number that does not follow the function defined in the if statement. The code as is, only loops once and then exits. Did I type the for loop incorrectly or is it the if...else statement that is wrong?
#include <iostream>
using std::cout; using std::cin; using std::endl;
int main() {
cout << "Enter a positive odd number less than 40: ";
int num = 0;
for (int a = 0; a < 3; ++a);
cin >> num;
{
if (num < 40 && num > 0 && num % 2 == 1)
{
cout << "Thank you!" << endl;
}
else cout << "That is incorrect, try again!" << endl;
}
}
Did I type the for loop incorrectly or is it the if...else statement that is wrong?
Both. You should (1) remove the semicolon following the for statment; (2) move cin >> num into the for loop body; (3) add break; inside the if.
for (int a = 0; a < 3; ++a)
{
cin >> num;
if (num < 40 && num > 0 && num % 2 == 1)
{
cout << "Thank you!" << endl;
break;
}
else cout << "That is incorrect, try again!" << endl;
}
BTW1: Try to use the debugger, then you'll find out what happened in fact.
BTW2: The code will fail when cin >> num fails (e.g. user entered an invalid value), you might need to check the result of cin >> num, to process the case. Such as:
for (int a = 0; a < 3; ++a)
{
if (cin >> num)
{
if (num < 40 && num > 0 && num % 2 == 1)
{
cout << "Thank you!" << endl;
break;
}
else cout << "That is incorrect, try again!" << endl;
}
else
{
cin.clear(); // unset failbit
cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n'); // skip bad input
cout << "Wrong input, try again!" << endl;
}
}
bool isValid = false;
int num;
while(!isValid)
{
cout << "enter a positive odd integer " << endl;
cin >> num;
if(num < 40 && num > 0 && num % 2 == 1 )
{
cout << "thank you"<<endl;
isValid = true;
}
else
isValid = false;
}
Why not use some thing like this, it will loop until isValid = true which will only happen when your conditions are met?
I understand I guess, if you're doing a school project or some thing and you're forced to do it with a for loop but in general this would be a much better solution for some thing like this than a for loop!
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I have some functions that need to be called multiple times, as such
int i;
i = 10;
while (i > 0)
{
selectletter(wordArray);
computerTurn(wordArray);
printGrid(grid);
i--;
}
The function selectletter works fine, and near the end of that function, it calls another function, "claimword". Claimword runs entirely fine, but at the end of the function, the program crashes when it runs out of context, as opposed to it just moving on to computerTurn as it should as shown above. I looked up on SO how to "exit" a function, and everyone said that "return;" would work fine, even in a void function. However, when I try using return, nothing at all happens, except for anything after the return statement is ignored. Can anyone tell me why the return statement doesn't work?
void claimword(Tile grid[7][6], char letter, string wordArray[100])
{
cout << "Would you like to claim a word? (Y/N)" << endl;
char chooseinput;
cin >> chooseinput;
if ((chooseinput == 'y') || (chooseinput == 'Y'))
{
printGrid(grid);
cout << "Please enter the word you would like to claim." << endl;
string input;
cin >> input;
int inthegrid = 0;
int errormessage = 0;
compchecker(grid, input, inthegrid);
int length;
if (inthegrid = 1)
{
for(int i = 0; i < 100; ++i)
{
if (input == wordArray[i])
{
if (input.find(letter) != std::string::npos)
{
string strl;
strl = wordArray[i];
length = strl.length();
cout << "You have claimed the word " << strl << endl;
wordArray[i] = "/";
}
else
{
errormessage = 1;
}
}
else
{
///cout << "Sorry, that word is not in the dictionary." << endl;
errormessage = 2;
}
}
if (errormessage = 1)
{
cout << "Sorry you cannot claim that word." << endl;
}
if (errormessage = 2)
{
cout << "Sorry, that word is not in the dictionary." << endl;
}
if (length == 3)
{
human.humanpoints = human.humanpoints + 1;
wordsthisturn = wordsthisturn + 1;
cout << "You have earned one point!" << endl;
}
if (length == 4)
{
human.humanpoints = human.humanpoints + 2;
wordsthisturn = wordsthisturn + 2;
cout << "You have earned two points!" << endl;
}
if (length == 5)
{
human.humanpoints = human.humanpoints + 4;
wordsthisturn = wordsthisturn + 4;
cout << "You have earned four points!" << endl;
}
if (length == 6)
{
human.humanpoints = human.humanpoints + 8;
wordsthisturn = wordsthisturn + 8;
cout << "You have earned eight points!" << endl;
}
if (length == 7)
{
human.humanpoints = human.humanpoints + 16;
wordsthisturn = wordsthisturn + 16;
cout << "You have earned sixteen points!" << endl;
}
else
{
cout << "Your word was too small to claim any points." << endl;
}
}
}
else
{
cout << "End of Player Turn." << endl;
//return;
}
cout <<"Test1";
return;
cout <<"Test2";
}
Regardless of the input I give it (y/n and such), "Test1" displays, but "Test2" doesn't. My theory is that the program doesn't return all the way, or I'm just simply not using it right.
EDIT:
With an edited statement in the main function,
selectletter(wordArray);
cout << "test11";
computerTurn(wordArray);
What should happen is that the selectletter function should be called. The selectletter function, at the end of it, calls another function, claimWord. claimWord is posted above. At the end of the function, it should end. There should be nothing left for it to do, and after all those if/elses regarding points, and even if no points are scored, or anything in the function happens, the function should end. The program should then display "test11", but it does not.
EDIT2:
void selectletter(string wordArray[100])
{
cout << endl;
cout << "REMAINING LETTERS:" << endl;
cout << human.humanletters << endl;
cout << "Select a letter.";
int length;
length = human.humanletters.size();
char input;
cin >> input;
int column;
int row = 7;
int cinput;
//mght have to change since 0 is the first val
cout << "What column would you like to drop that in? (1-7)";
cin >> cinput;
column = cinput - 1;
//cout << "Test1";
while (row > 0)
{
if (grid[row-1][column].active == true)
{
row--;
//cout << "Test3";
}
else
for(int i = 0; i < length; i++)
{
if(human.humanletters[i] == input)
{
//cout << "Test5";
human.humanletters.erase(std::remove(human.humanletters.begin(), human.humanletters.end(), input), human.humanletters.end());
grid[row-1][column].letter = input;
grid[row-1][column].active = true;
cout << endl;
//cout << "Test6";
claimword(grid, input, wordArray);
//this removes ALL instances of the letter, however
}
break;
//need to add something for if the letter is not in the string
//}
//row = 9999;
}
}
}
Regardless of the input I give it (y/n and such), "Test1" displays, but "Test2" doesn't.
That is what it is supposed to do. You called return after displaying Test1 and before displaying Test2, so the latter was skipped. return is an immediate return to the function that called the current function.
Your while loop has the condition while (row > 0), and you only decrement row when (grid[row-1][column].active == true). If that ever evaluates to false, you won't decrement row and your program runs forever.
Perhaps your break; was meant to break out of the while loop, but all it will do is break out of the for loop. A break statement breaks out of the nearest enclosing loop/switch block.
I have the following code and am trying to figure out how to have the option to return to the main menu by hitting any key, as long as the quit option isn't chosen. I assume something with this while loop is how it is done, but when I execute the code it terminates after 1 iteration. I'm just learning c++ so I'm not quite sure how to navigate through this problem.
//Runs a program with a menu that the user can navigate through different options with via text input
#include <iostream>
#include <cctype>
using namespace std;
int main()
{
char userinp;
cout<<"Here is the menu:" << endl;
cout<<"Help(H) addIntegers(A) subDoubles(D) Quit(Q)";
cin >> userinp;
userinp = tolower(userinp);
int count = 1;
while (count == 1)
{
if (userinp == 'h')
{
cout <<"This is the help menu. Upon returning to the main menu, input A or a to add 2 intergers." << endl;
cout <<"Input D or d to subtract 2 doubles. Input Q or q to quit.";
count = 1;
return count;
}
else if (userinp == 'a')
{
int a, b, result;
cout <<"Enter two integers:";
cin >> a >> b;
result = a + b;
cout << "The sum of " << a << " + " << b << " = " << result;
count = 1;
return count;
}
else if (userinp == 'd')
{
double a, b, result;
cout <<"Enter two integers:";
cin >> a >> b;
result = a - b;
cout << "The difference of " << a << " - " << b << " = " << result;
count = 1;
return count;
}
else if (userinp == 'q')
{
exit(0);
}
else
{
cout <<"Please input a valid character to navigate the menu - input the letter h for the help menu";
cout << "Press any key to continue";
count = 1;
return count;
}
}
}
remove
else
{
cout <<"Please input a valid character to navigate the menu - input the letter h for the help menu";
cout << "Press any key to continue";
count = 1;
return count;
}
and instead of while(count == 1) change it to while(true)//which means continously loop until q is pressed
also have this part inside while loop i.e
while(true)
{
cout<<"Here is the menu:" << endl;
cout<<"Help(H) addIntegers(A) subDoubles(D) Quit(Q)";
cin >> userinp;
userinp = tolower(userinp);
}
to have a prompt for continue:
1.add bool cond =true;(before while(true))
2.change while(true) to while(cond)
3.add this else block after else if (userinp == 'q') block
else
{ char ch;
cout << "Press y to continue";
cin>>ch;
if(ch=='y')
{
cond =true;
}
else
{
cond =false;
exit(0);
}
}