first commit

15 files changed, 259 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..cba7efc
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+a.out
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..9ec5d3b
--- /dev/null
+++ b/README.md
@@ -0,0 +1,2 @@
+Implementations of the exercises from The C Programming Language (2nd
+Edition) by Kernighan and Ritchie.
diff --git a/ch01/ex01-hello.c b/ch01/ex01-hello.c
new file mode 100644
index 0000000..53f4080
--- /dev/null
+++ b/ch01/ex01-hello.c
@@ -0,0 +1,6 @@
+#include <stdio.h>
+
+int main()
+{
+	printf("hello, world\n");
+}
diff --git a/ch01/ex02-exp.c b/ch01/ex02-exp.c
new file mode 100644
index 0000000..dcc46dd
--- /dev/null
+++ b/ch01/ex02-exp.c
@@ -0,0 +1,6 @@
+#include <stdio.h>
+
+int main()
+{
+	printf("hello, world\c");
+}
diff --git a/ch01/ex03-temp.c b/ch01/ex03-temp.c
new file mode 100644
index 0000000..b52e241
--- /dev/null
+++ b/ch01/ex03-temp.c
@@ -0,0 +1,21 @@
+#include <stdio.h>
+
+/* print Fahrenheit-Celsius table */
+int main()
+{
+	float fahr, celsius;
+	int lower, upper, step;
+
+	lower = 0;
+	upper = 300;
+	step = 20;
+
+	printf("%3s %6s\n", "F", "C");
+
+	fahr = lower;
+	while (fahr <= upper) {
+		celsius = (5.0/9.0) * (fahr-32.0);
+		printf("%3.0f %6.1f\n", fahr, celsius);
+		fahr = fahr + step;
+	}
+}
diff --git a/ch01/ex04-temp.c b/ch01/ex04-temp.c
new file mode 100644
index 0000000..f78a191
--- /dev/null
+++ b/ch01/ex04-temp.c
@@ -0,0 +1,21 @@
+#include <stdio.h>
+
+/* print Celsius-Fahrenheit table */
+int main()
+{
+	float celsius, fahr;
+	int lower, upper, step;
+
+	lower = 0;
+	upper = 300;
+	step = 20;
+
+	printf("%3s %6s\n", "C", "F");
+
+	celsius = lower;
+	while (celsius <= upper) {
+		fahr = celsius / (5.0/9.0) + 32.0;
+		printf("%3.0f %6.0f\n", celsius, fahr);
+		celsius = celsius + step;
+	}
+}
diff --git a/ch01/ex05-temp.c b/ch01/ex05-temp.c
new file mode 100644
index 0000000..6af87c6
--- /dev/null
+++ b/ch01/ex05-temp.c
@@ -0,0 +1,11 @@
+#include <stdio.h>
+
+/* print Fahrenheit-Celsius table, in reverse order */
+int main()
+{
+	int fahr;
+
+	for (fahr = 300; fahr >= 0; fahr = fahr - 20) {
+		printf("%3d %6.1f\n", fahr, (5.0/9.0)*(fahr-32));
+	}
+}
diff --git a/ch01/ex06-eof.c b/ch01/ex06-eof.c
new file mode 100644
index 0000000..bd8fae5
--- /dev/null
+++ b/ch01/ex06-eof.c
@@ -0,0 +1,6 @@
+#include <stdio.h>
+
+int main()
+{
+	printf("%d\n", getchar() != EOF);
+}
diff --git a/ch01/ex07-eof.c b/ch01/ex07-eof.c
new file mode 100644
index 0000000..f91bb75
--- /dev/null
+++ b/ch01/ex07-eof.c
@@ -0,0 +1,6 @@
+#include <stdio.h>
+
+int main()
+{
+	printf("%d\n", EOF);
+}
diff --git a/ch01/ex08-count.c b/ch01/ex08-count.c
new file mode 100644
index 0000000..c5052e6
--- /dev/null
+++ b/ch01/ex08-count.c
@@ -0,0 +1,22 @@
+#include <stdio.h>
+
+/* count blanks, tabs, and newlines in input */
+int main()
+{
+	int c;
+	int ns, nt, nl;
+
+	ns = 0;
+	nt = 0;
+	nl = 0;
+
+	while ((c=getchar()) != EOF) {
+		if (c == ' ')
+			++ns;
+		if (c == '\t')
+			++nt;
+		if (c == '\n')
+			++nl;
+	}
+	printf("%d %d %d\n", ns, nt, nl);
+}
diff --git a/ch01/ex09-copy.c b/ch01/ex09-copy.c
new file mode 100644
index 0000000..2303b83
--- /dev/null
+++ b/ch01/ex09-copy.c
@@ -0,0 +1,21 @@
+#include <stdio.h>
+
+/* merge consecutive blanks */
+int main()
+{
+	int c, b;
+
+	b = 0;
+	while ((c = getchar()) != EOF) {
+		if (c != ' ') {
+			putchar(c);
+			b = 0;
+		}
+
+		if (c == ' ') {
+			if (b == 0)
+				putchar(c);
+			b = 1;
+		}
+	}
+}
diff --git a/ch01/ex10-replace.c b/ch01/ex10-replace.c
new file mode 100644
index 0000000..b7ec4a5
--- /dev/null
+++ b/ch01/ex10-replace.c
@@ -0,0 +1,26 @@
+#include <stdio.h>
+
+/* replace each tab by \t, each backspace by \b, and each backslash by \\ */
+int main()
+{
+	int c;
+
+	while ((c = getchar()) != EOF) {
+		if (c == '\t') {
+			putchar('\\');
+			putchar('t');
+		}
+		if (c == '\b') {
+			putchar('\\');
+			putchar('b');
+		}
+		if (c == '\\') {
+			putchar('\\');
+			putchar('\\');
+		}
+		if (c != '\t')
+			if (c != '\b')
+				if (c != '\\')
+					putchar(c);
+	}
+}
diff --git a/ch01/ex11-wc.c b/ch01/ex11-wc.c
new file mode 100644
index 0000000..e2ec1d8
--- /dev/null
+++ b/ch01/ex11-wc.c
@@ -0,0 +1,35 @@
+#include <stdio.h>
+
+#define IN  1    /* inside a word */
+#define OUT 0    /* outside a word */
+
+/* count lines, words, and characters in input
+ *
+ * I would focus on testing the state transitions, since character and
+ * line counting are straightforward. The character count increments for
+ * every character that is not EOF, and the line count increments whenever
+ * a newline is encountered. Word counting is more complex because it
+ * depends on correctly detecting boundaries. I would include test cases
+ * with varying numbers of spaces, tabs, and newlines to verify that word
+ * boundaries are handled correctly, since those inputs are the most likely
+ * to reveal bugs.
+ */
+int main()
+{
+	int c, nl, nw, nc, state;
+
+	state = OUT;
+	nl = nw = nc = 0;
+	while ((c = getchar()) != EOF) {
+		nc++;
+		if (c == '\n')
+			++nl;
+		if (c == ' ' || c == '\n' || c == '\t')
+			state = OUT;
+		else if (state == OUT) {
+			state = IN;
+			++nw;
+		}
+	}
+	printf("%d %d %d\n", nl, nw, nc);
+}
diff --git a/ch01/ex12-print.c b/ch01/ex12-print.c
new file mode 100644
index 0000000..91aafa2
--- /dev/null
+++ b/ch01/ex12-print.c
@@ -0,0 +1,23 @@
+#include <stdio.h>
+
+#define IN  1    /* inside a word */
+#define OUT 0    /* outside a word */
+
+/* print one word per line from the input */
+int main()
+{
+	int c, state;
+
+	state = OUT;
+	while ((c = getchar()) != EOF) {
+		if (c == ' ' || c == '\n' || c == '\t') {
+			if (state == IN)
+				putchar('\n');
+			state = OUT;
+		} else if (state == OUT)
+			state = IN;
+		if (state == IN)
+			putchar(c);
+	}
+	putchar('\n');
+}
diff --git a/ch01/ex13-histogram.c b/ch01/ex13-histogram.c
new file mode 100644
index 0000000..14002a5
--- /dev/null
+++ b/ch01/ex13-histogram.c
@@ -0,0 +1,52 @@
+#include <stdio.h>
+
+#define IN  1    /* inside a word */
+#define OUT 0    /* outside a word */
+
+/* print a histogram of word lengths */
+int main()
+{
+	int c, i, j, nc, state;
+	int ndigit[10];
+
+	for (i = 0; i < 10; ++i)
+		ndigit[i] = 0;
+
+	nc = 0;
+	state = OUT;
+	while ((c = getchar()) != EOF) {
+		if (c == ' ' || c == '\n' || c == '\t') {
+			if (state == IN) {
+				i = nc - 1;
+				if (i > 9)
+					i = 9;
+				++ndigit[i];
+				nc = 0;
+			}
+			state = OUT;
+		} else if (state == OUT) {
+			state = IN;
+		}
+
+		if (state == IN)
+			++nc;
+	}
+
+	if (state == IN) {
+		i = nc - 1;
+		if (i > 9)
+			i = 9;
+		++ndigit[i];
+		nc = 0;
+	}
+
+	for (i = 0; i < 10; ++i) {
+		if (i == 9)
+			printf(" >9: ");
+		else
+			printf(" %2d: ", i + 1);
+		for (j = 0; j < ndigit[i]; ++j)
+			putchar('#');
+		putchar('\n');
+	}
+}