How to delete characters in vector of strings? - c++

Question

I am writing a code where I read a subtitle file and remove the text in () including the brackets themselves, that is subtitles for hearing impaired which have background noise in ().
The example:
13
00:01:08,535 --> 00:01:10,127 // remove this
(PIANO PLAYING) // remove this
125
00:07:09,162 --> 00:07:12,393
BOTH: (SINGING WITH RADIO) Teach // remove only the text in parenthesis, including ()
them well and let them lead the way
The code is here:
#include<iostream>
#include<fstream>
#include<string>
#include<vector>
using namespace std;
void subRem();
int main() {
subRem();
system("PAUSE");
}
void subRem() {
ofstream out;
ifstream in;
out.open("whip it2.srt");
if (out.fail()) {
perror("whip it2.srt");
}
in.open("whip it.srt");
if (out.fail()) {
perror("whip it.srt");
}
vector<string> input;
string inc;
while (getline(in, inc)) {
input.push_back(inc);
}
vector<int> len;
for (int i = 0; i < input.size(); i++) {
len.push_back(input[i].size());
}
for (int i = 0; i < input.size(); i++) {
for (int j = 0; j < len[i]; j++) {
if (input[i][j] == '(') {
for (int k = j; k < len[i]; k++) {
j = k;
if (input[i][k] == ')') {
if (k == (len[i] - 1)) {
input[i - 1] = "";
}
input[i][k] = '\0';
break;
}
input[i][k] = '\0';
}
}
}
}
for (int k = 0; k < input.size(); k++) {
out << input[k] << endl;
}
}
I want to delete the characters in parenthesis, so I am using:
input[i][k] = '\0';
The problem is the characters are removed but they are replaced by whitespace, for example:
(SHOUTING) with her?
I get:
___________with her?
(____ are whitespaces because I couldn't make them appear)
There is the white space. If it was string, I could do:
input[i][k] = "";
but with characters I get the error when I do:
input[i][k] = '';
quoted string should contain at least one character
I plan to improve the code further by renaming the line numbers and deleting extra newlines, but I want to create like an app where I can drag and drop the subtitle file and click run, to get the modified subtitle file. What do I need to know to create the GUI? Do I need to learn Qt or some other libraries?

Answer 1

std:;string can contain \0 without problems, it's not the end-of-string character inside a std::string. MikeCAT's suggestion is the correct answer: use std::string::erase.
(Please don't ask multiple questions at once, but yes Qt is a reasonable way to create GUI's)

Answer 2

Try using substr. This method gives you a substring between two given positions. Although this solves the problem for your second problem, it leaves empty subtitles for strings on the first case. I would recommend checking for an empty result and removing the string at all.

Answer 3

Since you're basically copying characters from one file to another, I'd just keep track of whether you're in a subtitle as you copy, and if so, don't copy characters until you encounter a close parenthesis again.
#include <string>
#include <iostream>
#include <sstream>
int main() {
std::istringstream in{
R"(13
00:01:08,535 --> 00:01:10,127
(PIANO PLAYING)
125
00:07:09,162 --> 00:07:12,393
BOTH: (SINGING WITH RADIO) Teach
them well and let them lead the way)"
};
bool in_subtitle = false;
std::string temp;
while (std::getline(in, temp)) {
unsigned line_len = 0;
for (char ch : temp) {
switch (ch) {
case '(': in_subtitle = true; break;
case ')': in_subtitle = false; break;
default:
if (!in_subtitle) {
std::cout << ch;
++line_len;
}
break;
}
}
if (line_len != 0) std::cout << "\n";
}
}

Answer 4

#include <iostream>
#include <regex>
int main() {
std::string text("this text (remove this) and (remove this) end.");
// First Method: with regular expression
std::regex expr("\\(.*?\\)");
std::cout << std::regex_replace (text, expr, "");
// Second Method: with stl
auto begin = text.find_first_of("(");
auto end = text.find_last_of(")") + 1;
if (std::string::npos != begin && std::string::npos != end && begin <= end)
text.erase(begin, end-begin);
// Optional
std::cout << text << std::endl;
}