Initial commit

4 files changed, 162 insertions, 0 deletions

diff --git a/three/conv.c b/three/conv.c
new file mode 100644
index 0000000..d3e654e
--- /dev/null
+++ b/three/conv.c
@@ -0,0 +1,65 @@
+#include <stdio.h>
+#include <limits.h>
+
+void
+reverse(char s[])
+{
+	int i = 0;
+	while (s[i] != '\0') {
+		++i;
+	}
+	--i;
+	char c;
+	for (int j = 0; j < i / 2; ++j) {
+		c = s[i - j];
+		s[i - j] = s[j];
+		s[j] = c;
+	}
+}
+
+void
+itoa(int n, char s[])
+{
+	int i, sign;
+	if ((sign = n) < 0) {
+		n = -n - 1;
+	}
+	i = 0;
+	do {
+		s[i++] = n % 10 + '0';
+	} while ((n /= 10) > 0);
+	if (sign < 0) {
+		s[i++] = '-';
+	}
+	s[i] = '\0';
+	reverse(s);
+}
+
+void
+itob(int n, char s[], int b)
+{
+	int i, sign;
+	if ((sign = n) < 0) {
+		n = -n;
+	}
+	i = 0;
+	do {
+		s[i++] = (n % b <= 9) ? n % b + '0' : n % b - 10 + 'a';
+	} while ((n /= b) > 0);
+	if (sign < 0) {
+		s[i++] = '-';
+	}
+	s[i] = '\0';
+	reverse(s);
+}
+
+int
+main()
+{
+	char s[32];
+	itoa(INT_MIN, s);
+	printf("%s\n", s);
+	itob(380, s, 16);
+	printf("%s\n", s);
+	return 0;
+}
diff --git a/three/escape.c b/three/escape.c
new file mode 100644
index 0000000..1f1dfe9
--- /dev/null
+++ b/three/escape.c
@@ -0,0 +1,53 @@
+#include <stdio.h>
+
+void
+ctoe()
+{
+	int c;
+	while ((c = getchar()) != EOF) {
+		if (c == '\\') {
+			c = getchar();
+			switch(c) {
+			case 'n':
+				putchar('\n');
+				break;
+			case 't':
+				putchar('\t');
+				break;
+			default:
+				putchar(c);
+				break;
+			}
+		} else {
+			putchar(c);
+		}
+	}
+}
+
+void
+etoc()
+{
+	int c;
+	while ((c = getchar()) != EOF) {
+		switch(c) {
+		case '\n':
+			putchar('\\');
+			putchar('n');
+			break;
+		case '\t':
+			putchar('\\');
+			putchar('t');
+			break;
+		default:
+			putchar(c);
+			break;
+		}
+	}
+}
+
+int
+main()
+{
+	etoc();
+	return 0;
+}
diff --git a/three/expand.c b/three/expand.c
new file mode 100644
index 0000000..180cc98
--- /dev/null
+++ b/three/expand.c
@@ -0,0 +1,19 @@
+#include <stdio.h>
+
+int
+main()
+{
+	int c, p;
+	while ((c = getchar()) != EOF) {
+		if (c == '-') {
+			c = getchar();
+			for (++p; p < c + 1; ++p) {
+				putchar(p);
+			}
+		} else {
+			putchar(c);
+		}
+		p = c;
+	}
+	return 0;
+}
diff --git a/three/search.c b/three/search.c
new file mode 100644
index 0000000..30426c7
--- /dev/null
+++ b/three/search.c
@@ -0,0 +1,25 @@
+#include <stdio.h>
+
+int
+binsearch(int x, int v[], int n)
+{
+	int low, high, mid;
+	low = 0;
+	high = n - 1;
+	while (low <= high) {
+		mid = (low + high) / 2;
+		if (x < v[mid]) {
+			high = mid - 1;
+		} else {
+			low = mid;
+		}
+	}
+	return -1;
+}
+
+int
+main()
+{
+	binsearch();
+	return 0;
+}