I would like to filter out any characters that not in the range of '0'.'9', 'a'.'z' or 'A'.'Z' given a text consists of words, letters, numbers,...

I would like to filter out any characters that not in the range of '0'..'9', 'a'..'z' or 'A'..'Z' given a text consists of words, letters, numbers, punctuations, and whitespaces.

for example, Sample Input

quick brown fox jumps over the lazy dog!

Sample Output

I have typed the codes as follow, however, the numbers are filtered out too.... Please help me. Thank you very much.

; { line; << ;getline(, line);( i = ; i < line.size(); ++i){ (!((line[i] >= && line[i]<=) || (line[i] >= && line[i]<=))){line[i] = ;}} ;}