enter image description here3(no of cases)
hello world
a b c d
data structures and algorithms.
Let say above is the given input format.Each string starts in a new line.Can i know how to read in the above way in cpp.I tried with getline function.It didn't work.
The getline method should work just fine. The following code works fine.
#include <iostream>
using namespace std;
int main(){
string s[3];
getline(cin, s[0]);
getline(cin, s[1]);
getline(cin, s[2]);
cout << s[0] << endl << s[1] << endl << s[2];
return 0;
}
EDIT:
After your clarification, it seems that the problem is actually that the buffer is not being cleared properly. So just use cin.ignore(); after cin >> t;
Refer to the code below:
#include <iostream>
using namespace std;
int main(){
int t;
cin >>t;
cin.ignore(); // This should clear the input buffer
string s;
getline(cin, s);
cout << s << endl;
return 0;
}
Related
I want to take in persons name using string object. But in my code if I put two part name separated with a space, only first part is displayed. My understanding is .c_str() returns a pointer to stored string with terminal null. Why is there a problem with space. I'm new to C++ and using Code::Blocks 13.12. This is a simplified version of the problem that I have in another program that I wrote.
Thanks in advance.
#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <cstring>
#include <string>
using namespace std;
int main()
{
string sCusName;
cout << "Please enter your name-> ";
cin >> sCusName;
int xsize = sCusName.length();
char *tempBuffer = new char[xsize+1];
strncpy(tempBuffer, sCusName.c_str(),xsize+1);
cout << tempBuffer << " is a beautiful name." << endl;
return 0;
}
When I enter single part name, program works fine. But if I put in two part name separated with space. Only first part is taken in.
it is not possible to read multi-word string using cin rather you should use getline() the getline() function takes two arguments cin and string variable forexample:
int main()
{
string sCusName;
cout << "Please enter your name-> ";
getline(cin,sCusName);
cout << sCusName << " is a beautiful name." << endl;
return 0;
}
I have a string with the value 788597.31 and I am converting this value to double but when I print the variable only 788597 is displayed. I have used std::stod(string) and even stringstream but everytime I get the same previous value. Can anybody help me with this?
I want to store this string value in a double varaible.
#include<iostream>
#include<string>
#include<sstream>
using namespace std;
int main()
{
string s="788597.31";
double d=stod(s);
cout<<d<<" ";
stringstream g;
double a;
g<<s; g>>a;
cout<<a;
return 0;
}
The problem is in how you are printing your result, not in the string parsing. This program:
#include <iostream>
using namespace std;
int main() {
cout << 788597.31 << endl;
return 0;
}
also prints 788597.
#include <iostream>
#include <iomanip>
using namespace std;
int main() {
cout << setprecision(10) << 788597.31 << endl;
return 0;
}
prints 788597.31
If you want to see more than the default 6 significant digits your program needs to say so.
I am trying to understand, then, write some code that has to read from, and write to many different files and do so from the main loop of my application. I am hoping to use the C++11 model present in VS 2013.
I don't want to stall the main loop so I am investigating spinning off a thread each time a request to write or read a file is generated.
I've tried many things including using the async keyword which sounds promising. I boiled down some code to a simple example:
#include <future>
#include <iostream>
#include <string>
bool write_file(const std::string filename)
{
std::cout << "write_file: filename is " << filename << std::endl;
std::this_thread::sleep_for(std::chrono::milliseconds(2000));
std::cout << "write_file: written" << std::endl;
return true;
}
int main(int argc, char* argv[])
{
const std::string filename = "foo.txt";
auto write = std::async(std::launch::async, write_file, filename);
while (true)
{
std::cout << "working..." << std::endl;
std::this_thread::sleep_for(std::chrono::milliseconds(100));
std::cout << "write result is " << write.get() << std::endl;
}
}
I'm struggling to understand the basics but my expectation would be that this code would constantly print "working..." and interspersed in the output would be the write_file start and end messages. Instead, I see that the write_file thread seems to block the main loop output until the timer expires.
I realize I need to also consider mutex/locking on the code to actually write the file but I would like to understand this bit first.
Thank you if you can point me in the right direction.
Molly.
write.get() will wait for the async task to finish. You want to use wait_for() instead:
do {
std::cout << "working...\n";
} while(write.wait_for(std::chrono::milliseconds(100)) != std::future_status::ready);
std::cout << "write result is " << write.get() << "\n";
# include <iostream>
# include <cmath>
using namespace std;
int main();
{
string color, plural noun, celebrity;
cout << "Enter a color: ";
getline(cin, color);
return 0;
}
There are errors in your code. Firstly, have you included #include <string> and #include <iostream> directives. Moreover, your code is as follows:
int main();{
string color, plural noun, celebrity;
cout<<"Enter a color: ";
getline(cin, color);
return 0;
}
However, if you notice, you have placed a semicolon (;) after the int main function, which might be giving you an error.
Also, as you were discussing in the comment section, declare plural noun as pluralNoun or plural_noun; never leave a space. I addition, a string is never called as cout<<"Roses are {color}"<<endl;, strings have to be called as:
#include<iostream>
#include <string>
int main();{
string color, pluralNoun, celebrity;
cout << "Enter a color: ";
getline(cin, color);
cout << "Roses are " << color << endl;
cout << "Enter a plural noun: ";
getline(cin,pluralNoun);
cout << pluralNoun << "are blue" << endl;
return 0;
}
The code above and your latter code; if executed in the same way as above will definitely not give you an error. Hope this helped you overcome the problem! :)
I am pretty new to yaml-cpp. After did tutorials, that tutorials are fine. But When I try to Parse my own yaml file, it's a litte difficult for me. I am confused with "operator" and "node".
yaml file is shown below.
Device:
DeviceName: "/dev/ttyS2"
Baud: 19200
Parity: "N"
DataBits: 8
StopBits: 1
Control:
Kp: 5000
Ki: 8
FVF: 100
VFF: 1962
Could you anyone give me an example to get data from that yaml file? thanks for your help.
Also i followed this question , I can build it. But When I run it, I got Segmentation fault (core dumped)
Code:
#include <yaml-cpp/yaml.h>
#include <string>
#include <iostream>
using namespace std;
int main()
{
YAML::Node config = YAML::LoadFile("init.yaml");
//read device
std::string DeviceName = config["Device"][0]["DeviceName"].as<std::string>();
int Baud = config["Device"][1]["Baud"].as<int>();
std::string Parity = config["Device"][2]["Parity"].as<std::string>();
int DataBits = config["Device"][3]["DataBits"].as<int>();
int StopBits = config["Device"][4]["StopBits"].as<int>();
//read control
int Kp = config["Control"][0]["Kp"].as<int>();
int Ki = config["Control"][1]["Ki"].as<int>();
int FVF = config["Control"][2]["FVF"].as<int>();
int VFF = config["Control"][3]["VFF"].as<int>();
cout <<"DeviceName" << DeviceName << endl;
cout <<"Baud" << Baud << endl;
cout <<"Parity" << Parity << endl;
cout <<"DataBits" << DataBits << endl;
cout <<"StopBits" << StopBits << endl;
cout <<"Kp" << Kp << endl;
cout <<"Ki" << Ki << endl;
cout <<"FVF" << FVF << endl;
cout <<"VFF" << VFF << endl;
return 0;
}
your code above results in a bad conversion exception because you access the map items in a wrong way.
instead of
std::string DeviceName = config["Device"][0]["DeviceName"].as<std::string>();
just write
std::string DeviceName = config["Device"]["DeviceName"].as<std::string>();
best regards
robert