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ifstream myfile;//file reading mode
myfile.open("file2.txt");//file opened
if(!myfile)
{
cout<<"your file cannot be opened";
}
for(;!myfile.eof();)
{
myfile>>name>>salary>>concerned_department;
cout<<name<<"\t"<<salary<<"\t"<<concerned_department<<"\n";
}
do
{
cout<<"To search an employee please enter the name of the employee<<"\n";
cin>>empName;//will take the string from the user.
cout<<empName<<"\n";
ifstream myfile;//file reading mode
myfile.open("file2.txt");//file opened successfully
if(strcmp(name,"empName")==0)//here the main problem lies
{
myfile>>name>>salary>>concerned_department;
cout<<name<<"\t"<<salary<<"\t"<<concerned_department<<"\n";
}
else
{//
cout<<"ERROR "could not be compared"<<"\n";
}
cout<<"Do you want to continue (y/n)";
cin>>con;
}
while(con=='y');
The strcmp() function is not comparing the strings though given. string1 is given in the file whereas the string2 is being taken from the user.
Use the following code:
if(strcmp(name,empName)==0)
{
...
}
Note that there must be no quotation marks around empName to compare its contents.
Related
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I came across this question while practicing Pointer questions and according to my understanding I thought option C would be correct but Option D was the correct answer, so I ran the code on VS Code and it did give a Compilation error.
Strings are terminated by NULL character then why an error is occurring if the for loop is checking for the occurrence of the NULL character.
Please can somebody explain what is the problem with this code? Here is the actual code:
#include<iostream>
using namespace std;
int main() {
char st[] = "ABCD";
for(int i = 0; st[i] != ‘\0’; i++) {
cout << st[i] << *(st)+i << *(i+st) << i[st];
}
return 0;
}
‘ (U+2018 LEFT SINGLE QUOTATION MARK) and ’ (U+2019 RIGHT SINGLE QUOTATION MARK) are Unicode characters, and your source file is saved in UTF-8.
You likely copied this code from some website which used these characters.
You need to use ASCII ' (U+0027 APOSTROPHE) instead:
st[i] != '\0'
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I have read these two questions already:
Remove spaces from std::string in C++
remove whitespace in std::string
For some reason, I can never get the solutions to work correctly. In my program, I collect input from the user and pass it to an std::string. From there, I want to remove all of the spaces in it. For example, if the user inputs "3 + 2", I would like it to change to "3+2".
What happens is, whatever is before the first string is kept. Here is my program:
#include <iostream>
std::string GetUserInput() {
std::cout << "Please enter what you would like to calculate: ";
std::string UserInput;
std::cin >> UserInput;
return UserInput;
}
int PerformCalculation(std::string Input) {
Input.erase(std::remove_if(Input.begin(), Input.end(), ::isspace), Input.end());
std::cout << Input;
return 0;
}
int main() {
std::string CalculationToBePerformed = GetUserInput();
int Solution = PerformCalculation(CalculationToBePerformed);
return 0;
}
So when I run this program and type in "3 + 2", the output is "3".
Here is my console:
Please enter what you would like to calculate: 3 + 2
3
Process finished with exit code 0
I cannot figure out how to resolve this. I even tried using a solution that involved using a regex to remove all the \s characters, and that gave me the same issue.
To read the complete line (up to terminating \n), you need to use e.g. std::getline(std::cin, UserInput);. Otherwise, you're currently reading text up to first whitespace character.
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while(true) {
getline(myfile, a[i]);
if (a[i]=="")//or if(a[i].empty())
break;
i++;
n = i;
}
In this while loop, when getline function gets a blank line from myfile object (there is a blank line between a series of binary numbers).
Example:
101010
000
11
1
00
<- when getline meets this line, by "if" break; has to work.
0011
10
00111
1101
But, it doesn't realize that blank line.
What is wrong?
What should I code to break when getline() meets the blank line?
I do this through PuTTY.
You are most likely running into the NL/CR issue.
Instead of
if (a[i]=="")
Use something like:
if (isEmptyLine(a[i]))
where
bool isEmptyLine(std::string const& s)
{
for ( auto c : s )
{
if ( !std::isspace(c) )
return false;
}
return true;
}
You can also convert the file into a file with UNIX style line endings by using a utility called dos2unix. That should also fix the problem.
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I'm new to time complexity in algorithms.
This is the code for counting the number of words in a text file.
My problem is that every time my program prints one more than the actual count of words in the file, like if I have 11 words in my file it prints 12.
#include<fstream>
#include<iostream>
#include<string>
using namespace std;
/* main function */
void main()
{
ifstream inFile; //file file name
string fileName;
string word;
int count = 0;
inFile.open("example.txt");
while(!inFile.eof())
{
inFile >> word;
++count;
}
cout << "Number of words in file is " << count<<endl;
inFile.close();
}
//this file is for counting the number of words in a text file**
First thing first : Why is iostream::eof inside a loop condition considered wrong? This will answer your extra count problem.
Then, coming to complexity, since it will go though every N words till it reaches end of file, it will be done in O( N ) time
Also, void main() is not legal c++, main should return int
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This function is supposed to open a .txt file like this:
1 4 5
2 4 6
etc. (with tab between numbers)
and save each number in one variable
void Graph::readData(char* fname)
{
//cout<<"1";
int x,y,w;//assistant variables
ifstream input;//stream for reading file
input.open(fname,ios::in);
if(!input)
{
cerr<<"Input file doesn't exist"<<endl;//error if file doens exist
}
else
{
cout<<"Input file opened"<<endl;
cout<<"Reading Data from file..."<<endl;
while(!input.eof())//till the end of file
{
input>>x>>y>>w;//reads the links-site
cout<<"x: "<<x<<"y:"<<y<<"w: "<<w<<endl;
insertLink(x,y,w);//inserts them
}
input.close();//closing file
}
}
However, when I "cout" the results I get something like this:
x=1 y= w=5
x=2 y= w=6
without y!
Why could this happen?
PS: In addition, eof() becomes true after the file is finished (reads one extra line). How can I stop while iteration properly?
This is the file I'm trying to read from: http://www.speedyshare.com/tpvuD/input.txt
To stop the iteration properly, write the loop as:
while(input>>x>>y>>w)//till the end of file
{ /* ... */ }
Do not check input.eof().