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I want to print out the number entered by the user as a whole and want to ignore the spaces.
Like this:
int aValue;
cin >> aValue;
Here, suppose the user enters 49 506, I want to print it as 49506.
First you need to get a string from a user with spaces, note you need to use std::getline() for that, as operator>> would not accept spaces:
std::string str;
std::getline( cin, str );
then you use std::remove_if() together with std::isspace() to remove spaces from your string:
auto it = std::remove_if( str.begin(), str.end(), []( unsigned char c ) { return std::isspace(c); } );
str.erase( it, str.end() );
and then you convert your string to an int using std::stoi():
auto aValue = std::stoi( str );
you should also add error checking to your code handling error conditions as described in documentation.
Related
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I would like to parse a sentence beginning with a number:
2 random sentece.
5 another one.
8 this is really long sentence.
Into int number holding the beginning number and the rest in std::string sentence. So in the first line, the parsing output will be number == 2 and sentence == "random sentence". The input is read from stdin, but the classical std::cin >> number >> sentence does'n work, since the parsing of string would end once it reaches a space. But I want to make the string beginning after the initial number to the end of line \n. So, how to do it in C++?
You can make use of std::getline and std::istringstream as shown below. In particular in the given program, std::getline is used to read line by line and std::istringstream is used to read first the integer and then the remaining sentence.
#include <iostream>
#include <string>
#include <sstream>
int main()
{
std::string sentence;
int inputInt = 0;
//read line by line
while(std::cin >> inputInt && std::getline(std::cin, sentence))
{
std::cout<< inputInt <<"-----"<<sentence<<std::endl;
//do the check here
}
}
Demo
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I've asked to write code that gets a char array(sentence), if the there is an 'i' in the sentence I need to add the letter 'b' the letter 'i' again like this example:
pig -> pibig
I tried to use string.h functions but I didn't succeed to make it right.
Use std::string in string header file, and std::string::insert whenever you need to insert a char in string:
std::string my_string = "my satringa";
for (size_t i = 0; i < my_string.length(); ++i)
{
if (my_string.at(i) == 'a')
{
my_string.insert(i + 1, "b");
}
}
std::clog << my_string << std::endl;
Output:
> my sabtringab
If you are forced to use C-style strings, don't worry do all of your operations on std::string and then take the underlying stored string with std::string::c_str() as a C-style string (and don't forget to take a copy).
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I'm need to create id just number. For example: 12345678
If user inputs fail( contain char), delete char immediately.
For example: 123a =>input gain!
Please help me!
I think this is what you are looking for:
#include <iostream>
#include <string>
#include <cctype>
int main () {
std::string input;
bool valid;
do {
valid = true;
std::cin >> input;
for (char c : input)
if (! std::isdigit( static_cast<unsigned char>(c) ) )
valid = false;
} while (! valid);
// Here the string is guaranteed to be valid
}
Be aware though, that whatever you are trying to do, this does not look like the proper way to do it. There are ways to read numbers in c++, and this is not what I would recommend.
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My .txt file is like this:
question1 answer1
question2 answer2
question3 answer3
How can I place question1 and answer1 into two separate variables? I can use getLine(), but it will return the question and answer.
If each question is terminated with a question mark then you can write
std::string line;
while ( std::getline( FileStream, line ) )
{
std::istringstream is( line );
std::string question;
std::string answer;
std::getline( is, question, '?' );
question += '?';
std::getline( is, answer );
// some processing of question and answer
}
If there is used some other separator then you need to substitute the question mark for this separator and maybe to remove line
question += '?';
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getline(cin,s);
istringstream iss(s);
do
{
string sub;
iss>>sub;
q.insert(sub);
}while(iss);
I used this technique when question wanted me to split on the basis of space so can anyone explain me how to split when there's a particular delimiter like ';' or ':'.
Someone told me about strtok function but i am not able to get it's usage so it would be nice if someone could help.
First, don't use strtok. Ever.
There's not really a function for this in the standard library.
I use something like:
std::vector<std::string>
split( std::string const& original, char separator )
{
std::vector<std::string> results;
std::string::const_iterator start = original.begin();
std::string::const_iterator end = original.end();
std::string::const_iterator next = std::find( start, end, separator );
while ( next != end ) {
results.push_back( std::string( start, next ) );
start = next + 1;
next = std::find( start, end, separator );
}
results.push_back( std::string( start, next ) );
return results;
}
I believe Boost has a number of such functions. (I implemented
most of mine long before there was Boost.)