How can I remove values from output statement given a condition? - c++ - c++

I'm a little confused as to how to go around this. I have some array variables with some information, and I want to print them out after some calculations. If the value is 0, then I want to print a " " instead. There are 3 arrays that need to get checked however, how would I change the output statement to cater for all 3 checks and print an empty string instead of the value?
for(int start = 1; start < 13; start++)
{
if(check[start] == 1)
{
cout << checkMonth(start) << ": " << setprecision(1) << fixed << averagespeed[start] << "(" << setprecision(1) << fixed << sdSpeed[start] << ")," << setprecision(1) << fixed << averagetemp[start] << "(" << setprecision(1) << fixed << sdTemp[start] << ")," << setprecision(1) << fixed << Solar[start] << '\n';
}
/*if(sumTemp[start] == 0 || sumTemp[start] == 0 || sumSpeed[start] == 0){
}*/
}
Example Output looks like this:
January,5.5(1.2),25.5(12.2),196.4
For example if Sum of Speed is 0, that means all values of speed were 0 or null. So it should change to this:
January,,25.5(12.2),196.4

A single line to std::cout doesn't need to be done in one statement. For example:
std::cout << "First";
std::cout << ", second"
std::cout << ", third\n"
Prints the following line:
First, second, third
Now we can use an if to conditionally print the middle part of the string:
std::cout << a;
if (b != 0) {
std::cout << ", " << b;
}
std::cout << ", " << c << '\n';

Related

simple game, while loop and checking strings

I am a beginner at c++ and I want to create simple game. You have vector of strings, then you check if line input matched the right answer.
I want to generate random number 1 ,2 or 3. Then check if line matches correct answer and count the points.
I am probably missing something basic, yet I dont know what.
Problems:
Input line get correctly read on only first iterations
somehow points (tocke) jumps to 45763 after finishing.
At beginning time (cas) is sometimes 2.
Code:
#include <iostream>
#include <vector>
#include <stdlib.h>
#include <time.h>
#include <string>
int main() {
int runde;
int tocke;
int cas;
std::cout << "\n" << "Pravila igre:" << "\n" << "Za pravilen odgovor dobis 1 tocko, za napacnega zgubis 2!"<<
"\n" << "Stevilo zivljenj si izberes sama!"<< "\n" << "\n" ;
std::cout << "Izberi stevilo zivljenj!:" << "\n";
std::cin >> runde ;
std::vector<std::string> latin = {"carum carvi", "artemisia absiinthium","coriandrum sativum"};
std::vector<std::string> slovene = {"navadna kumina", "pravi pelin", "koriander"};
tocke << 0;
cas << 0;
do {
int ind;
cas << cas + 1;
std::cout << "Round " << cas <<"! Ladies and gentlemans, buckle your seatbelts!"<<"\n" << "\n" ;
ind = std::rand() % 3;
std::cout << "ime rastline: " << slovene[ind] << "\n";
std::cin.ignore();
std::string line;
getline(std::cin, line);
std::cout << "\n";
if (latin[ind] == line){
std::cout << "Pravlino! Tocka zate!" << "\n";
tocke << tocke + 1;
std::cout << "Tocke == " << tocke << "\n" << "Zivjenja == " << runde << "\n" << "Prezivete runde == " << cas << "\n"<< "\n";
}
else
{
std::cout << "Napaka! :D" << "\n";
std::cout << "Pravilen odgovor == " << latin[ind] << "\n";
-- runde ;
tocke << tocke - 2;
std::cout << "Tocke == " << tocke << "\n" << "Zivjenja == " << runde << "\n" << "Prezivete runde == " << cas << "\n"<< "\n";
}
}while(runde >= 0 );
std::cout << "\n"<<"Stevilo tock == " << tocke <<"\n" << "St. prezivetih rund == " << cas - 1
<< "\n" ;
}
You seem to have a misconception regarding operators. << is NOT assignment, use = instead. So tocke << 0; doesn't assign 0 to tocke, it does bitshifting (on an uninitialized variable), then discards the result. tocke stays uninitialized and this causes problems later.
Instead of this:
tocke << 0;
cas << 0;
Do this:
tocke = 0;
cas = 0;
Also instead of cas << cas + 1; do cas++ and instead of tocke << tocke - 2; do tocke -= 2;. To learn how the assignment operators work, you can read about them here. Last but not least, try to see if your compiler gives you any warnings, it should complain about using uninitialized values.

I need to have spaces between outputted _

I have just more or less finished my first C++ Project, it is a Hangman Game and so far everything works fine. The only Problem is that i need to have spaces between the underlines (_) that represent the hidden word. If anyone could help me on this i would really appreciate it.
// UNCOMMENT THE FOLLOWING LINE (REMOVE THE TWO SLASHES AT THE BEGINNING) TO RUN AUTOMATIC TESTS
#include "tests.h"
#include <iostream>
#include <string>
#include "hangman.h"
int main(){
using namespace std;
// display the hidden word
std::string word_to_guess = chooseWord();
int misses = 0;
std::string displayed_word = word_to_guess;
for(int i=0; i< displayed_word.length(); i++)
displayed_word[i] = '_';
int attempts = 6;
std::cout << "Attempts left:" << attempts << std::endl;
std::cout << "[ " << displayed_word << " ]" << std::endl;
//check for correct letter
while(1){
std::cout << "Your guess";
std::cout << ":";
char guess;
std::cin >> guess;
bool Correct = false;
for(int i=0; i< word_to_guess.length(); i++)
if (guess == word_to_guess[i]) {
displayed_word[i] = word_to_guess[i];
Correct = true;
}
if (!Correct)
attempts--;
if (!Correct)
std::cout << "Attempts left:" << attempts << std::endl;
if (!Correct)
std::cout << "[ " << displayed_word << " ]" << std::endl;
if (Correct)
std::cout << "Attempts left:" << attempts << std::endl;
if (Correct)
std::cout << "[ " << displayed_word << " ]" << std::endl;
//check for win or lose
if (attempts==0)
std::cout << "The word was: " << word_to_guess << std::endl << "You lost!";
if (attempts==0)
return 0;
if (!word_to_guess.find(displayed_word))
std::cout << "You won!";
if (!word_to_guess.find(displayed_word))
return 0;
}
}
First, you can simplify this
if (!Correct)
std::cout << "Attempts left:" << attempts << std::endl;
if (!Correct)
std::cout << "[ " << displayed_word << " ]" << std::endl;
if (Correct)
std::cout << "Attempts left:" << attempts << std::endl;
if (Correct)
std::cout << "[ " << displayed_word << " ]" << std::endl;
by this
std::cout << "Attempts left:" << attempts << std::endl;
std::cout << "[ " << displayed_word << " ]" << std::endl;
Now, about your question, I think a best solution is replacing
std::cout << "[ " << displayed_word << " ]" << std::endl;
by this
std::cout << "[";
for(int i = 0; i < displayed_word.length(); i++) {
if(i == 0 || displayed_word[i] == '_')
std::cout << " ";
std::cout << displayed_word[i];
if(i == displayed_word.length()-1 || (displayed_word[i] == '_' && displayed_word[i+1] != '_'))
std::cout << " ";
}
std::cout << "]" << std::endl;
Explaination:
We put spaces at the beginning and the end, and also around underscores, but we make sure to put only one space between two underscores.

C++ - Multiplying / adding, two integers, then determining if they are even or odd

I'm having trouble with a simple program which will multiply 2 integers and print the output determining if it is even or odd. It also will add the 2 integers input in the beginning and do the same on the following line. The multiplying works fine and displays if the product is even or odd properly. However, the addition is not doing so and I am not understanding why. Here is my code:
#include <iostream>
using namespace std;
int main (){
int a, b;
cout << "Please enter an integer: ";
cin >> a;
cout << "Please enter another integer: ";
cin >> b;
if (a*b %2== 0){
cout << "The product of " << a << " and " << b << " is " << (a*b)
<< " and is even." << endl;
}
else {
cout << "The product of " << a << " and " << b << " is " << (a*b)
<< " and is odd." << endl;
};
if (a+b %2== 0){
cout << "The sum of " << a << " and " << b << " is " << (a+b)
<< " and is even." << endl;
}
else {
cout << "The sum of " << a << " and " << b << " is " << (a+b)
<< " and is odd." << endl;
}
return (0);
}
Any help and an explanation would be greatly appreciated. Thanks!
Operator Precedence
Basically, % is dealt with before +, so your test:
if (a+b % 2 == 0)
works out like
if (a + (b%2) == 0)
which doesn't make a whole lot of sense, and is rarely going to be true, unless both b is even and a is 0.
All the operations that are to do with multiplication (*, /, %) have the same precedence, and are handled from left-to-right, so
if (a*b % 2 == 0)
works out ok, as:
if ((a*b) % 2 == 0)
which happens to be what you really meant.
However, these multiplication operations are handled before the operations related to addition (+, -). So % is grouped before +, causing your specific problem.
You may have learnt about order of operations in school, for instance I was taught BODMAS. Same rules apply in C++.
Personally, I find it's best to use parentheses liberally in any sort of compound expression, even when it's not strictly necessary. It can make the code a lot easier to read, rather than trying to remember all the rules in your head. So I would prefer:
if ((a*b) % 2 == 0) // ...
if ((a+b) % 2 == 0) // ...
even though the extra parentheses in the first aren't really required.
Operator precedence says that % comes before + so
a+b %2== 0
Is actually
a + (b % 2) == 0
You need to wrap the addition with ()
(a + b) % 2 == 0
Possibly Order of Operations.
To ensure that your code is behaving the way you intend, you may wish to rewrite it like this:
if (((a*b) %2)== 0){
cout << "The product of " << a << " and " << b << " is " << (a*b) << " and is even." << endl;
}
else {
cout << "The product of " << a << " and " << b << " is " << (a*b) << " and is odd." << endl;
};
if (((a+b) %2)== 0){
cout << "The sum of " << a << " and " << b << " is " << (a+b) << " and is even." << endl;
}
else {
cout << "The sum of " << a << " and " << b << " is " << (a+b) << " and is odd." << endl;
}
You can then incrementally remove parenthesis until you're confident that the code is readable but still correct.

comparing what two pointers point to

I'm writing a program to detect phishing. I'm trying to check if the base of the URL, if it is same in the tag or not.
For e.g. in http://maps.google.com"> www.maps.yahoo.com
I'm trying to check if the last 2 parts of the URL are same or not, i.e. if google.com = yahoo.com or not.
I'm using the following code to do so:
void checkBase(char *add1, char *add2){
char *base1[100], *base2[100];
int count1 = 0, count2 = 0;
base1[count1] = strtok(add1, ".");
while(base1[count1] != NULL){
count1++;
base1[count1] = strtok(NULL, ".");
}
base2[count2] = strtok(add2, ".");
while(base2[count2] != NULL){
count2++;
base2[count2] = strtok(NULL, ".");
}
if((base1[count1-1] != base2[count2-1]) && (base1[count1-2] != base2[count2-2])){
cout << "Bases do not match: " << endl
<< base1[count1-2] << "." << base1[count1-1] << " and "
<< base2[count2-2] << "." << base2[count2-1] << endl;
}
else{
cout << "Bases match: " << endl
<< base1[count1-2] << "." << base1[count1-1] << " and "
<< base2[count2-2] << "." << base2[count2-1] << endl;
}
}
I'm not sure if i'm comparison in the if statement is right or not. I'm passing in two URL's.
Thanks
this is comparing the two pointers char* (as you point out;) )
base1[count1-1] != base2[count2-1])
use this instead
strcmp(base1[count1-1], base2[count2-1]) != 0
you could use std:string and boost tokenizer (now C++11 I think)
regards
You can't compare strings by comparing their addresses, two identical strings can be stored in different addresses. To compare them you should you strcmp:
if(strcmp(base1[count1-1], base2[count2-1]) != 0 ||
strcmp(base1[count1-2], base2[count2-2])!=0){
std::cout << "Bases do not match: " << std::endl
<< base1[count1-2] << "." << base1[count1-1] << " and "
<< base2[count2-2] << "." << base2[count2-1] << std::endl;
}
You can do similar with C++ tools:
void checkBase(std::string a1, std::string a2){
size_t a1_start = a1.rfind('.'), a2_start = a2.rfind('.');
a1_start = a1.rfind('.', a1_start-1);
a2_start = a2.rfind('.', a2_start-1);
std::string h1 = a1.substr(a1_start+1), h2 = a2.substr(a2_start+1);
if (h1 == h2)
std::cout << "same" << std::endl;
else
std::cout << "not same" << std::endl;
}

Char array outputting extra characters

Hello this is a segment of my code of which i am trying to implement the Morris-Pratt algorithm.
When i am comparing my variables if find that they dont match, this is because one of my variables "Temp" is geting extra characters added to the end of the array.
here is my code...
// Calculate the next talbe
char test[searchLen];
for(int i = 0; i < searchLen; i++)
{
test[i] = fileContent[currPos+i];
}
cout << "SEARCHLEN: " << searchLen << endl;
cout << "TEST: " << '\t' << '\t' << test << endl;
cout << "SEARCH: " << '\t' << search << endl;
cout << strcmp(test,search) << endl << endl;
// Determine if a match is detected
if(strcmp(test,search)==0)
{
cout << "----------------------> Match detected at: " << currPos << endl;
}
currPos ++;
}
return numberOfComparisons;
}
The output looks like this...
SEARCHLEN: 8
TEST: athsoutg5?h
SEARCH: brilling
-1
As you can see the 5?H is not supposed to be there and is breaking my code.
You need to add a null terminator.
char test[searchLen + 1];
test[searchLen] = '\0';
It does look like your string is not terminated with \0, maybe you forgot to copy it / put it in there?