fix: empty file, empty arg work

ex04/src/main.cpp

@@ -0,0 +1,66 @@
+#include <cstddef>
+#include <ostream>
+#include <string>
+#include <iostream>
+#include <fstream>
+#include <cstring>
+
+static int get_text(const char *path, std::string &text)
+{
+	std::ifstream	file(path);
+	std::string		line;
+
+	if (!file.is_open())
+	{
+		std::cerr << "sed: file error" << std::endl;
+		return (1);
+	}
+	while (std::getline(file, line))
+		text += line + "\n";
+	if (text.size() != 0)
+		text.erase(text.size() - 1);
+	file.close();
+	return (0);
+}
+
+static std::string	replace_text(const char *text, const char *text_to_replace, const std::string &replacement_text)
+{
+	size_t		i;
+	size_t		len;
+	std::string	out;
+
+	len = std::strlen(text_to_replace);
+	i = 0;
+	while (text[i] != '\0')
+	{
+		if (len != 0 && std::strncmp(text + i, text_to_replace, len) == 0)
+		{
+			out += replacement_text;
+			i += len;
+		}
+		else
+		{
+			out += text[i];
+			i++;
+		}
+	}
+	return (out);
+}
+
+int main(int ac, char **av)
+{
+	std::string text;
+	std::string replaced;
+
+	if (!(ac >= 4))
+	{
+		std::cerr << "Sed: missing argument" << std::endl
+			<< "syntax: ./sed file text_to_replace replacement_text" << std::endl;
+		return (1);
+	}
+	if (get_text(av[1], text))
+		return (2);
+	std::cout << text << std::endl;
+	replaced = replace_text(text.c_str(), av[2], av[3]);
+	std::cout << replaced << std::endl;
+}