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I am a newbie in C++, I started to learn coding in C++ two weeks ago. Why does my code below always give me result 0 when I build and run? Please help
# include <iostream>
# include <string>
using namespace std;
int main ()
{
int input = 1;
cout << "input your number : \n";
cin >> input;
int faktorial = 1;
for(int i=1;i<=input;i++)
{
faktorial = faktorial * i;
}
cout << "factorial value from number " << input << " is " << faktorial << endl;
}
Your code works: https://ideone.com/CYFaxo
I suspect your problem is, you are looking at program exit code. When you don't return any value from main, program exit code is 0 (this is special case, and only non-void function where you may leave the return statement out), which conventionally means success (non-zero exit code usually indicates some kind of error, by convention).
Try to find the program output from your IDE, it should have the correct printout.
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My "num = -num" line inside of my "if (num<0)" line still affects results, even if my input is greater than 0.
#include <iostream>
int main()
{
std::cout << "Enter a positive number: ";
int num{};
std::cin >> num;
if (num < 0)
std::cout << "Negative number entered. Making positive.\n";
num = -num;
std::cout << "You entered: " << num;
return 0;
}
To have multiple statements inside an if, you must use brackets.
And at this point of learning the language, I would recommend just always using brackets.
if (num < 0) {
std::cout << "Negative number entered. Making positive.\n";
num = -num;
}
Unlike languages like python, leading whitespace is not meaningful to the compiler in C++.
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I have simplified the code to get rid of unrelated objects. This is my code:
#include <iostream>
#include <fstream>
using namespace std;
fstream asdf;
int input;
void import_image(){
asdf.seekg(0);
char character;
for(int k = 0; k < 40; k++){
asdf.get(character);
input = (unsigned int)(unsigned char)character;
}
}
void print_hello_world(){
for(int rows; rows <= 27; rows++){
cout << "hello world" << endl;
}
cout << "goodbye.";
}
int main(){
asdf.open("abc.txt", ios::binary | ios::in);
cout << asdf.is_open() << endl;
import_image();
//cout << endl;
print_hello_world();
return 0;
}
Running this code results only in
1
goodbye.
--------------------------------
Process exited after 0.1511 seconds with return value 0
however removing double slash (simply adding cout << endl;) fixes everything. I have no idea why it happens and would like to now why is it so. I know that variable "rows" has no value, but why does printing a new line fix everything?
The new "endl"
is a great sign
that what you see,
is called "UB".
Your program has Undefined Behavior (UB) because your int rows that you use for the loop iterations is uninitialized.
By UB definition anything may happen. Activate all (sane) compiler warnings to find errors like this earlier in your development process.
Undefined behavior yield working programs by completely random changes (for example the addition of std::endl) but in the end it's undefined behavior.
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My while loop is not working. The code runs correctly on the Codecademy website compiler. I then compile it with Visual Studio, run it from the Command prompt and input a number. The program stops prematurely even if the number is the correct one.
#include <cstdlib>
#include <iostream>
int main() {
int answer = 8;
int guess;
int tries;
std::cout << "I have a number between 1-10.\n";
std::cout << "Please guess it: ";
std::cin >> guess;
while (guess != 8 && tries < 50) {
std::cout << "Wrong guess, try again: ";
std::cin >> guess;
tries++;
}
if (guess == 8) {
std::cout << "You got it!\n";
}
}
As #rsjaffe and #Ken White have said in the comments, the tries variable is unitiailized, meaning that the location in memory that the variable is pointing to is "junk" (left over memory). Try to give it an initial value, like this:
int tries = 0;
which will instantiate and initialize the tries variable.
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I'm a student who just learned to use C++ for a few weeks. I write C++ code on Code:: Block and I am trying to run this code to learn about vector:
#include <iostream>
#include <vector>
#include <string>
using namespace std;
int main()
{
vector<int> intVector;
for(int i = 0; i < 10; i++)
{
intVector.push_back(i+1);
}
cout << "Numbers in vector: ";
for(int i = 0; i < intVector.size(); i++)
{
cout << intVector[i] + " ";
}
}
But the output is really weird:
Numbers in vector: vector::_M_emplace_back_auxector::_M_emplace_back_auxctor::_M_emplace_back_auxtor::_M_emplace_back_auxor::_M_emplace_back_auxr::_M_emplace_back_aux::_M_emplace_back_aux:_M_emplace_back_aux_M_emplace_back_aux
Process returned 0 (0x0) execution time : 0.047 s
Press any key to continue.
Does anyone know how to fix this problem? Do I use vector in the wrong way?
Try changing the cout line like this:
cout << intVector[i] << " ";
What you're trying to do is add an int& and a string literal -- in some compilers it will emit a warning indicating for you that you're not getting what you intended for.
For example with Clang:
warning: adding '__gnu_cxx::__alloc_traits>::value_type' (aka 'int') to a string does not append to the string [-Wstring-plus-int]
cout << intVector[i] + " ";
~~~~~~~~~~~~~^~~~~
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What have I done wrong with the following code?
#include <iostream>
using namespace std;
main ()
{
int a;
int b;
int sum;
cout << "Enter first number \n";
cin >> a;
cout << "Enter second number \n";
cin >> b;
sum = a+b;
cout << "The sum of both numbers is" << sum << endl;
return 0;
}
Does the editor you are using tells errors, so the code is not executing? Or som exception rises? Or it is executing but nothing is shown? Please specify your problem accurately.
Anyway, you must use
int main ()
instead of
main()
Notice that your code returns a value. The last line of you code is:
return 0;
Thus, you must specify an int return type.
Check your initial lines with this.
#include <iostream>
using namespace std;
int main ()
{