From de32013d6c59126470c41f7eb57d28ad460b0127 Mon Sep 17 00:00:00 2001
From: NaiJi <naijiworld@protonmail.com>
Date: Thu, 2 May 2024 15:15:30 +0400
Subject: [PATCH] 1.21

---
 The C Programming Language/1.21.c | 59 +++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)
 create mode 100644 The C Programming Language/1.21.c

diff --git a/The C Programming Language/1.21.c b/The C Programming Language/1.21.c
new file mode 100644
index 0000000..c6dd7f2
--- /dev/null
+++ b/The C Programming Language/1.21.c	
@@ -0,0 +1,59 @@
+#include <stdio.h>
+
+
+int _getline(char s[], int lim)
+{
+	int c, i, j;
+	for (i = 0; (c = getchar()) != '\n'; ++i)
+	{
+		if (i < lim - 1)
+			s[i] = c;
+	}
+
+	j = i;
+	if (j > lim - 1)
+		j = lim - 1;
+	s[j] = '\0';
+	return j - 1;
+}
+
+void entab(char to[], char from[], int columns)
+{
+	int spaces_counter = 0;
+	int from_i = 0;
+	int to_i = 0;
+
+	while (from[from_i] != '\0')
+	{
+		++spaces_counter;
+		++from_i;
+		if (spaces_counter == columns)
+		{
+			to[to_i] = '\t';
+			++to_i;
+			spaces_counter = 0;
+		}
+	}
+
+	while (spaces_counter > 0)
+	{
+		to[to_i] = '_';
+		++to_i;
+		--spaces_counter;
+	}
+
+	to[to_i] = '\0';
+}
+
+main()
+{
+	int size = 500;
+	char from[size];
+	char to[size];
+	while (1)
+	{
+		_getline(from, size);
+		entab(to, from, 4);
+		printf("%s\n", to);
+	}
+}