string - deleting ALL comment lines that start with // c++ -

string - deleting ALL comment lines that start with // c++ -

string str; cout << "enter code\n"; getline(cin, str, '~'); //some loop can't figure out size_t nfpos = str.find('//'); size_t sec = str.find('\n', nfpos); size_t first = str.rfind('\n', nfpos); str.erase(first, sec - first); //end unknown loop

input

code

//comment

//comment

code~

output

code

//comment

code

i cannot life of me figure out kind of loop should utilize delete comments starting //. it's deleting first comment , bypassing else.

i've tried for, while, while, , if

i can't figure out

you should utilize

while(true) { size_t nfpos = str.find('//'); if(nfpos + 1) { size_t sec = str.find('\n', nfpos); size_t first = str.rfind('\n', nfpos); str.erase(first, sec - first); } else { break; } }

as mentioned here

while executing std::find(), if no matches found, function returns string::npos

which defined static const size_t npos = -1;

so whenever match found it'll homecoming position of first character of first match, (so it'll non -1 ).

if unable find match it'll homecoming -1 , else section executed (because -1+1=0 , 0 equivalent false ), taking out of loop

c++ string loops comments erase