How do I run the while loop until the end of line or null character reached.
Here is my code
#include<iostream>
using namespace std;
main()
{
char input[20];
cout<<"Enter a line: ";
cin>>input;
while(input!='\0')
{
cout<<"This is a text";
}
system("pause");
}
If you want to read until either a newline or a NUL, read one character at a time inside the loop.
#include<iostream>
int main()
{
char input;
std::cout << "Enter a line: " << std::flush;
while(std::cin >> input && input != '\n' && input != 0) {
std::cout << "This is a test\n";
}
}
Notes:
cout
to appear immediately. while
condition:
'\\n'
(one of your conditions). But, consider if you have correctly specified your requirement. It is an unusual requirement -- why would there be a NUL in a text file, and why would you want to process each character individually?
In idiomatic C++, you can read the input file in a line at a time using std::getline
:
std::string myString;
while(std::getline(std::cin, myString)) {
// process myString
}
If you just want to read in a single line:
std::string myString;
if(std::getline(std::cin, myString)) {
// process myString
}
Finally, if you want to read a line, and ignore its contents:
std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
Like this:
std::string line;
if (std::getline(std::cin, line))
{
std::cout << "Thank you, you said, \"" << line << "\".\n";
}
else
{
// error, e.g. EOF
}
If you want to read multiple lines, use a while
loop instead:
while (std::getline(std::cin, line))
{
std::cout << "Thank you, you said, \"" << line << "\".\n";
}
try something like:
i = 0;
while ((input[i] != '\0') && i < 20)
{
cout<<"This is a text";
i++;
}
The issue is that you're reading an entire chunk of text at once and then printing it until the input is '\\0'. However, you're never actually updating this inside the loop. You can either use cin inside the loop to get the input, OR if you're trying to output each character, you can index the char array.
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