take a single charakter from string
Hello,
I have made a program which reads a string from the user and store it in a vector,
but i have a small problem.
I want something that "reads" the string and if the second position of string is a number i want to store that number in an integer so as to use it..
for example:
string line;
int k;
getline(cin,line);
line[1]==k;
last command is not right but i need something that is able to do it.
string is unknown until user puts it.
**string can be mixed numbers and characters** i just need to take line[1] if only it is a number..
Thanks in advance.
I have made a program which reads a string from the user and store it in a vector,
but i have a small problem.
I want something that "reads" the string and if the second position of string is a number i want to store that number in an integer so as to use it..
for example:
string line;
int k;
getline(cin,line);
line[1]==k;
last command is not right but i need something that is able to do it.
string is unknown until user puts it.
**string can be mixed numbers and characters** i just need to take line[1] if only it is a number..
Thanks in advance.
Last edited on
if i give this string ":2" , i want to take 2 and use it..
if i give this string ":12",i want to take 12 and use it..
if i give this string ":12",i want to take 12 and use it..
OK, you'll need to use stringstreams in that case
http://www.cplusplus.com/reference/iostream/stringstream/
They are like other streams ( like cin/cout/fstream ) but they operate on strings
eg:
To check whether the second character of the string is a number you can use isdigit from <cctype>
http://www.cplusplus.com/reference/clibrary/cctype/isdigit/
http://www.cplusplus.com/reference/iostream/stringstream/
They are like other streams ( like cin/cout/fstream ) but they operate on strings
eg:
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To check whether the second character of the string is a number you can use isdigit from <cctype>
http://www.cplusplus.com/reference/clibrary/cctype/isdigit/
error :
variable `std::stringstream ss' has initializer but incomplete type
may i have to put some special header except from <iostream> ,<fstream> ??
variable `std::stringstream ss' has initializer but incomplete type
may i have to put some special header except from <iostream> ,<fstream> ??
my code is the following :
#include <iostream>
#include <vector>
#include <fstream>
#include <cstdlib>
#include <sstream>
using namespace std;
int main()
{
vector<string> vectorOne;
vector<string> vectorTwo;
string line ;
int i , k ;
for(i=1; ; i++){
cout << i << ">";
getline(cin,line);
vectorOne.push_back(line);
stringstream ss ( line.substr (1) );
ss >> k;
if(line[0]==':'){
if(line[1]=='s'){
vectorOne.erase(vectorOne.end());
for(i=0; i < (long) vectorOne.size(); i++){
cout << i+1 << ">" << vectorOne.at(i) <<endl;
}
}
if(line[1]=='q') break;
if(line[1]=='c'){
vectorOne.clear();
i=0;
}
if(line[1]=='a'){
vectorOne.erase(vectorOne.end());
i=i-1;
}
if(line[1]==k){
i=k-1;
}
}
if(line==":i myout.txt"){
vectorOne.erase(vectorOne.end());
ifstream inputFile("myout.txt");
while(getline(inputFile, line)){
vectorTwo.push_back(line);
}
vectorOne.insert(vectorOne.begin(),vectorTwo.begin(),vectorTwo.end());
i=i-1;
}
if(line==":w myout.txt"){
vectorOne.erase(vectorOne.end());
ofstream outputFile("myout.txt");
for(long index=0; index< (long) vectorOne.size(); index++){
outputFile << vectorOne.at(index) << endl ;
}
outputFile.close();
i=i-1;
}
}
system("PAUSE");
return 0;
}
i want to link 'k' with 'if'.. is it possible??
#include <iostream>
#include <vector>
#include <fstream>
#include <cstdlib>
#include <sstream>
using namespace std;
int main()
{
vector<string> vectorOne;
vector<string> vectorTwo;
string line ;
int i , k ;
for(i=1; ; i++){
cout << i << ">";
getline(cin,line);
vectorOne.push_back(line);
stringstream ss ( line.substr (1) );
ss >> k;
if(line[0]==':'){
if(line[1]=='s'){
vectorOne.erase(vectorOne.end());
for(i=0; i < (long) vectorOne.size(); i++){
cout << i+1 << ">" << vectorOne.at(i) <<endl;
}
}
if(line[1]=='q') break;
if(line[1]=='c'){
vectorOne.clear();
i=0;
}
if(line[1]=='a'){
vectorOne.erase(vectorOne.end());
i=i-1;
}
if(line[1]==k){
i=k-1;
}
}
if(line==":i myout.txt"){
vectorOne.erase(vectorOne.end());
ifstream inputFile("myout.txt");
while(getline(inputFile, line)){
vectorTwo.push_back(line);
}
vectorOne.insert(vectorOne.begin(),vectorTwo.begin(),vectorTwo.end());
i=i-1;
}
if(line==":w myout.txt"){
vectorOne.erase(vectorOne.end());
ofstream outputFile("myout.txt");
for(long index=0; index< (long) vectorOne.size(); index++){
outputFile << vectorOne.at(index) << endl ;
}
outputFile.close();
i=i-1;
}
}
system("PAUSE");
return 0;
}
i want to link 'k' with 'if'.. is it possible??
Please use [code][/code] tags
I don't know what you mean but in
If you want to check if the second character is a number ( digit ) use the function I mentioned above
I don't know what you mean but in
if(line[1]==k) you are comparing an int with a character.If you want to check if the second character is a number ( digit ) use the function I mentioned above
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if you run this code then it will ask you to enter a string.. I save that string in a vector.
output : 1>
2>
etc
command :s --> shows the context of the vector
command :c --> clears the vector
command :w myout.txt --> saves vector in myout.txt
command :i myout.txt
:s --> shows the index of the .txt file
i want to make the following command :
:12 --> this command will show me line 12 and whatever i write will erase the vector at 12
and repace it with the new line tha i will write.
that's why i want to connect 'if' with 'k'..
Last edited on
Why do you require the input starting with ':' ?
Why are you hard-coding the job that a parser should do?
Why are you hard-coding the job that a parser should do?
It's an exercise for my university... if i don't give it then i will fail to lesson...
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