I am trying to skip the spaces in my code using getline();
I think I solved the spacing problem, but I'm trying to make the code check from the beginning of the word and the end of the word at the same time, so that when I type sentences like "ufo tofu" it will come back as a palindrome.
I've tried removing the spaces, but it only causes the system to return me an error.
#include <iostream>
#include <string>
#include <cctype>
using namespace std;
int main() {
string userInput;
int startInput;
int endInput;
bool isPalindrome = true;
startInput = userInput.length();
getline (cin, userInput);
cin.ignore();
for (int i = 0; i<(startInput/2); i++){
if (userInput[i] != userInput[(startInput -1) -i])
isPalindrome = false;
}
if (isPalindrome){
cout << userInput << " is a palindrome" << endl;
}
else {
cout << userInput << " is not a palindrome" << endl;
}
return 0;
}
I am trying to make the output come back as "is not a palindrome" when I submit my code to be graded.
These are the two errors that are coming back;
4: Compare output
0 / 2
Output differs. See highlights below.
Special character legend
Input
statistics
Your output
statistics is a palindrome
Expected output
statistics is not a palindrome
6: Compare output
0 / 2
Output differs. See highlights below.
Special character legend
Input
evil is alive
Your output
evil is alive is a palindrome
Expected output
evil is alive is not a palindrome
string s;
do {
getline(cin, s);
}while(s.empty());
s.erase((remove(s.begin(),s.end(),' ')),s.end());
cout<<s<<endl;
Let's say your string s is ufo tofu. It will after erasing all spaces become ufotofu. That way you can easily check if it's palindrome or not.
How does this thing work ?
Well we declare a string called s. In that string, we will store our ufo tofu input.
We use do-while loop to input our "sentence" into a string. We could use just getline(cin, s);, but if you pressed enter-key once, it would stop your program.
Next thing, we use function combination of functions remove and erase: As the beginning parameter we use function remove, which finds all the spaces in the string, pushes them to the end of the container (in our case string s), and returns beginning iterator of that "pushing", and the second parameter tells us to remove every single element of container from that beginning iterator to the end.
We just print out the string, but now without spaces!
I think this is really simple way to do it, but if it can't be useful to you, I am sorry for wasting your time reading all of this! :)
Related
I was using character arrays to get inputs from the user then display the output afterwards. However, every time I enter values with spaces in between, only the first word before the space is printed.
For instance, this is what I typed:
Customer No.: 7877 323 2332
This will be the output:
Customer No.: 7877
I already searched for possible solutions but I can't seem to find the right solution.
This is my code for reference:
#include<iostream>
using namespace std;
int main()
{
char custNum[10] = " "; // The assignment does not allow std::string
cout << "Please enter values for the following: " << endl;
cout << "Customer No.: ";
cin >> custNum;
cout << "Customer No.: " << custNum << endl;
}
Another option is to use std::basic_istream::getline to read the entire string into the buffer and then remove the spaces with a simple for loop. But when using plain-old character arrays don't skimp on buffer size. It is far better to be 1000-characters too long than one-character too short. With your input, your absolute minimum size of custNum is 14 characters (the 13 shown plus the '\0' (nul-terminating) character. (rough rule-of-thumb, take your longest estimated input and double it -- to allow for user-mistake, cat stepping on keyboard, etc...)
In you case you can simply do:
#include <iostream>
#include <cctype>
int main() {
char custNum[32] = " "; // The assignment does not allow std::string
int wrt = 0;
std::cout << "Please enter values for the following:\nCustomer No.: ";
if (std::cin.getline(custNum, 32)) { /* validate every input */
for (int rd = 0; custNum[rd]; rd++)
if (!isspace((unsigned char)custNum[rd]))
custNum[wrt++] = custNum[rd];
custNum[wrt] = 0;
std::cout << "Customer No.: " << custNum << '\n';
}
}
The two loop counters rd (read position) and wrt (write position) are simply used to loop over the original string and remove any whitespace found, nul-terminating again when the loop is left.
Example Use/Output
$ ./bin/readcustnum
Please enter values for the following:
Customer No.: 7877 323 2332
Customer No.: 78773232332
Also take a look at Why is “using namespace std;” considered bad practice? and C++: “std::endl” vs “\n”. Much easier to build good habits now than it is to break bad ones later... Look things over and let me know if you have questions.
Apart from std::getline, if you are going to use C-style strings, try the following code:
int main() {
char* str = new char[60];
scanf("%[^\n]s", str); //accepts space a a part of the string (does not give UB as it may seem initially
printf("%s", str);
return 0;
}
Also, if you absolutely need it to be a number, then use atoi
int ivar = std::atoi(str);
PS Not to forget gets (!!dangerous!!)
char* str;
gets(str);
puts(str);
cin >> int_variable will stop reading input when it reaches the first character that isn't a valid part of a number. C++ does not consider spaces part of a number, so it stops reading as soon as it encounters one.
You could use std::getline to read into a string instead, then remove the spaces from the string before converting to an integer. Or maybe in this case you don't even need the integer and can leave it as a string.
I picked up a challenge on r/dailyprogrammer on reddit which wants me to match a necklace and put the last letter at the beginning of a string. I've considered using nested for loops for this but this has made me really confused.
Instead I chose the way of replacing the last with the first character in an if-statement. But I am not getting my desired output with it, though I've tried everything what comes into my mind.
I used even std::swap() which didn't lead me to success either.
Here's the code:
#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
string same_necklace(string& sInput, string& sOutput)
{
for (string::size_type i = 0; i < sInput.size(); i++)
{
if (sInput[i] == sInput.size())
{
sInput[0] = sInput[sInput.size()];
}
}
for (string::size_type j = 0; j < sOutput.size(); j++)
{
if (sOutput[j] == sOutput.size() - 1)
{
sOutput[0] = sOutput[sOutput.size()];
}
}
return sInput, sOutput;
}
int main()
{
system("color 2");
string sName{ "" };
string sExpectedOutput{ "" };
cout << "Enter a name: ";
cin >> sName;
cout << "Enter expected output: ";
cin >> sExpectedOutput;
cout << "Result: " << same_necklace(sName , sExpectedOutput) << endl;
return 0;
}
And of course the link to my challenge (don't worry, it's just Reddit!):
https://www.reddit.com/r/dailyprogrammer/comments/ffxabb/20200309_challenge_383_easy_necklace_matching/
While I am waiting (hopefully) for a nice response, I will keep on trying to solve my problem.
In your if you compare the value of the current index (inside the loop) with the size of the string. Those are two unrelated things.
Also, you use a loop though you only want to do something on a single, previously known index.
for (string::size_type i = 0; i < sInput.size(); i++)
{
if (sInput[i] == sInput.size())
{
sInput[0] = sInput[sInput.size()];
}
}
You could change the if condition like this to achieve your goal:
if (i == sInput.size()-1) /* size as the index is one too high to be legal */
But what is sufficient and more elegant is to drop the if and the loop. completely
/* no loop for (string::size_type i = 0; i < sInput.size(); i++)
{ */
/* no if (sInput[i] == sInput.size())
{*/
sInput[0] = sInput[sInput.size()-1]; /* fix the index*/
/* }
} */
I.e.
sInput[0] = sInput[sInput.size()-1]; /* fix the index*/
Same for he output, though you got the correct index already correct there.
This is not intended to solve the challenge which you linked externally,
if you want that you need to describe the challenge completely and directly here.
I.e. this only fixes your code, according to the desription you provide here in the body of your question,
"put the last letter at the beginning of a string".
It does not "switch" or swap first and last. If you want that please find the code you recently wrote (surely, during your quest for learning programming) which swaps the value of two variables. Adapt that code to the two indexes (first and last, 0 and size-1) and it will do the swapping.
So much for the loops and ifs, but there is more wrong in your code.
This
return sInput, sOutput;
does not do what you expect. Read up on the , operator, the comma-operator.
Its result is the second of the two expressions, while the first one is only valuated for side effects.
This means that this
cout << "Result: " << same_necklace(sName , sExpectedOutput) << endl;
will only output the modified sExpectedOutput.
If you want to output both, the modified input and the modified output, then you can simply
cout << "Result: " << sName << " " << sExpectedOutput << endl;
because both have been given as reference to the function and hence both contain the changes the function made.
This also might not answer the challenge, but it explains your misunderstandings and you will be able to adapt to the challenge now.
You have not understand the problem i guess.
Here you need to compare two strings that can be made from neckless characters.
Lets say you have neckless four latters word is nose.
Combination is possible
1)nose
2)osen
3)seno
4)enos
your function (same_necklace) should be able to tell that these strings are belongs to same necklace
if you give any two strings as inputs to your function same_necklace
your function should return true.
if you give one input string from above group and second input string from other random word thats not belongs to above group, your function should return false.
In that sense, you just take your first string as neckless string and compare other string with all possible combination of first string.
just move move you first latter of first input string to end and then compare each resulting string to second input string.
below is the function which you can use
void swap_character(string &test)
{
int length = test.length();
test.insert(length, 1, test[0]);
test.erase(0, 1);
}
I'm told to ask the user for a string ( a sentence). Then the user is asked to input another string to search in string 1 (the sentence). The program has to count the number of times the second string shows up in the first string. I'm not getting any errors but it's is not counting the letters. This is the result i get:
Enter a sentence:i love to eat soup
Enter string to search: ou
There are 0 of the string ou in the first string you provided.
Can someone please tell me what i'm doing wrong? I'm a beginner at c++ so i'm having some trouble understanding.
#include <iostream>
#include <string>
using namespace std;
int main() {
string sentence;
string search;
int count = 0;
cout<<"Enter a sentence:";
getline (cin, sentence);
cout<<"Enter string to search:";
getline (cin, search);
cout << "There are " << count << " of the string " << search << " in the first string you provided." <<"\n";
for (int i=0; i < sentence.size(); ++i)
{
if (sentence == search)
count++;
}
return count;
}
Two issues:
You print count before you calculate it.
You are not actually searching for a substring. You should look at the documentation for std::string to find an appropriate way to search for substrings. However, you are on the right track.
Well, you're trying to output the results before calculating them.
Also, == is for exact matches, not substring searches.
You have your cout print line after the loop where you search for the string and set the count. Move it below that loop.
looks like you should put the cout statement in the end of this method. Because in your code, count is always 0 when you output it
You should modify your loop so that it really searches for substrings and count their occurrences:
string::size_type pos = sentence.find(search);
while (pos != string::npos)
{
pos = sentence.find(search, pos + search.size());
count++;
}
Also, you most likely want to move this line after the point where you actually compute the value of count:
cout << "There are " << count << ...
Otherwise, it will obviously output the value to which count was initialized originally (i.e. 0).
This may be a total beginner's question, but I have yet to find an answer that works for me.
Currently, I'm writing a program for a class that takes in a user's input (which can be one or more numbers separated by spaces), then determines whether the number is prime, perfect, or neither. If the number is perfect, then it will display the divisors.
Thus far, I've already written the code for the prime, perfect, and listing the divisors. I'm stuck on the input portion of my program. I don't know how to get the input that's separated by spaces to go through my loops one at a time.
This is my current program:
cout<<"Enter a number, or numbers separated by a space, between 1 and 1000."<<endl;
cin>>num;
while (divisor<=num)
if(num%divisor==0)
{
cout<<divisor<<endl;
total=total+divisor;
divisor++;
}
else divisor++;
if(total==num*2)
cout<<"The number you entered is perfect!"<<endl;
else cout<<"The number you entered is not perfect!"<<endl;
if(num==2||num==3||num==5||num==7)
cout<<"The number you entered is prime!"<<endl;
else if(num%2==0||num%3==0||num%5==0||num%7==0)
cout<<"The number you entered is not prime!"<<endl;
else cout<<"The number you entered is prime!"<<endl;
return 0;
It works, but only for a single number. If anyone could help me to get it to be able to read multiple inputs separated by spaces, it'd be greatly appreciated. Also, just a side note, I do not know how many numbers will be entered, so I can't just make a variable for each one. It will be a random amount of numbers.
Thanks!
By default, cin reads from the input discarding any spaces. So, all you have to do is to use a do while loop to read the input more than one time:
do {
cout<<"Enter a number, or numbers separated by a space, between 1 and 1000."<<endl;
cin >> num;
// reset your variables
// your function stuff (calculations)
}
while (true); // or some condition
I would recommend reading in the line into a string, then splitting it based on the spaces. For this, you can use the getline(...) function. The trick is having a dynamic sized data structure to hold the strings once it's split. Probably the easiest to use would be a vector.
#include <string>
#include <vector>
...
string rawInput;
vector<String> numbers;
while( getline( cin, rawInput, ' ' ) )
{
numbers.push_back(rawInput);
}
So say the input looks like this:
Enter a number, or numbers separated by a space, between 1 and 1000.
10 5 20 1 200 7
You will now have a vector, numbers, that contains the elements: {"10","5","20","1","200","7"}.
Note that these are still strings, so not useful in arithmetic. To convert them to integers, we use a combination of the STL function, atoi(...), and because atoi requires a c-string instead of a c++ style string, we use the string class' c_str() member function.
while(!numbers.empty())
{
string temp = numbers.pop_back();//removes the last element from the string
num = atoi( temp.c_str() ); //re-used your 'num' variable from your code
...//do stuff
}
Now there's some problems with this code. Yes, it runs, but it is kind of clunky, and it puts the numbers out in reverse order. Lets re-write it so that it is a little more compact:
#include <string>
...
string rawInput;
cout << "Enter a number, or numbers separated by a space, between 1 and 1000." << endl;
while( getline( cin, rawInput, ' ') )
{
num = atoi( rawInput.c_str() );
...//do your stuff
}
There's still lots of room for improvement with error handling (right now if you enter a non-number the program will crash), and there's infinitely more ways to actually handle the input to get it in a usable number form (the joys of programming!), but that should give you a comprehensive start. :)
Note: I had the reference pages as links, but I cannot post more than two since I have less than 15 posts :/
Edit:
I was a little bit wrong about the atoi behavior; I confused it with Java's string->Integer conversions which throw a Not-A-Number exception when given a string that isn't a number, and then crashes the program if the exception isn't handled. atoi(), on the other hand, returns 0, which is not as helpful because what if 0 is the number they entered? Let's make use of the isdigit(...) function. An important thing to note here is that c++ style strings can be accessed like an array, meaning rawInput[0] is the first character in the string all the way up to rawInput[length - 1].
#include <string>
#include <ctype.h>
...
string rawInput;
cout << "Enter a number, or numbers separated by a space, between 1 and 1000." << endl;
while( getline( cin, rawInput, ' ') )
{
bool isNum = true;
for(int i = 0; i < rawInput.length() && isNum; ++i)
{
isNum = isdigit( rawInput[i]);
}
if(isNum)
{
num = atoi( rawInput.c_str() );
...//do your stuff
}
else
cout << rawInput << " is not a number!" << endl;
}
The boolean (true/false or 1/0 respectively) is used as a flag for the for-loop, which steps through each character in the string and checks to see if it is a 0-9 digit. If any character in the string is not a digit, the loop will break during it's next execution when it gets to the condition "&& isNum" (assuming you've covered loops already). Then after the loop, isNum is used to determine whether to do your stuff, or to print the error message.
You'll want to:
Read in an entire line from the console
Tokenize the line, splitting along spaces.
Place those split pieces into an array or list
Step through that array/list, performing your prime/perfect/etc tests.
What has your class covered along these lines so far?
int main() {
int sum = 0;
cout << "enter number" << endl;
int i = 0;
while (true) {
cin >> i;
sum += i;
//cout << i << endl;
if (cin.peek() == '\n') {
break;
}
}
cout << "result: " << sum << endl;
return 0;
}
I think this code works, you may enter any int numbers and spaces, it will calculate the sum of input ints
std::vector<int> num{};
int buf;
do{
std::cin >> buf;
num.push_back(buf);
}while(std::cin.peek() == ' ');
In C language you can to it using scanf like this:
scanf('%d %d',&a,&b);
I've come this far without asking for help, but I've got a problem that I can't seem to fix. I like cryptology, so now that I am learning C++, I want to make programs to encrypt and decrypt strings. I read that the best way is to convert the text to ASCII and go from there, so here is a simple program I made in C++ to try and convert a char variable to ASCII:
#include <iostream>
#include <string>
#include <math.h>
using namespace std;
int main()
{
char strString[1000];
cout<<"Enter you message:"<<endl;
cin>>strString[1000];
string strEncrypt;
int a = 0;
while (strString != '\0')
{
int b = (int)strString[a];
strEncrypt.at(a) = b; //This is where I'm getting an error.
a++;
}
cout<<"Encrypted message:"<<endl;
cout<<strEncrypt<<endl;
}
So, I've tried all 3 things I know to do to troubleshoot (Google, check for missing simicolons, and make sure I'm doing == not =, but this is just something I don't know how to do, not something I'm forgetting (I hope). So, any help would great!
You don't have to change the characters to ASCII they already are. Chars are basically the same as integers in memory.
Now to your question; . If you want to set a character in a string you can do that like this
string[index] = b;
Another thing to be careful for in your code. You are using cin to read the string from the user. This will not let you read messages that have spaces in them and will only read the first word. For example, if the user enters "Love Crypto" cin will only read "Love" and "Crypto" will be ignored. To get the entire line, use getline instead.
As for looping over characters in a string, it's better to do it as follows:
for(int i = 0; i < strString.length(); i++)
{
strString[i] = bla;
}
Again, you're code isn't actually doing anything. It is only reading a letter and then storing a "letter" in another string.
string::at() throws exception if the index passed to at() is out of range. So, if you are getting runtime error then it's expected. Because, your string strEncrypt is initialized to "" and thus the size is 0.
You may try
strEncrypt.reserve(strlen(strString));
Easiest way to actually make the code you have work is change this line strEncrypt.at(a) = b; to this strEncrypt += b; Which will add the characters to the empty string strEncrypt.
Your code doesn't make much sense though as char types are already ascii. You'll have to explain more about what kind of encrypting you are trying to do and maybe we can point you in the right direction.
EDIT: After thinking about what you're trying to do a bit more based on the code you have it seems like you want to print the numeric ascii value of characters. You can do that with just a cast like this:
string input;
cout << "Enter you message:" << endl;
// handle spaces in the message
getline(cin, input);
cout << "String chars as ascii values:" << endl;
cout << "Char: " << "ASCII Code:" << endl;
for (int i = 0; i < input.length(); ++i)
{
// casting the char to an int with (int) will print the ascii code
cout << input[i] << " " << (int)input[i] << endl;
}
On top of the fact that your input is already in ASCII, keep in mind that doing cin >> strString[1000] doesn't limit the input captured to the length of your buffer unless you specifically specify the number of characters to capture for the stream object using setw() or setting it's ios_base::width data member. So your method right now risks buffer overflows.
Secondly, the form of cin >> that you're using will not capture the entire line of input. Instead it will stop at the first white-space or any other delimiting character (or end-of-file if that is reached first). In your case, if you are entering a line like "Hello World", then the syntax you're using will only capture "Hello" and drop "World".
A much better idea would be to use the getline() function with a std::string object if you are wanting to capture a line of input to a string and remove the delimiting newline character without risking buffer overflows ... for instance:
string strString;
getline(cin, strString);
Apart from advises given, when receiving this kind of run-time errors use Cppcheck utility.
It will give you the answer: "Message: Array 'strString[1000]' index 1000 out of bounds".