diff --git a/chapter_3.control_flow/3_04.itoa/Makefile b/chapter_3.control_flow/3_04.itoa/Makefile
new file mode 100644
index 0000000..1f10e34
--- /dev/null
+++ b/chapter_3.control_flow/3_04.itoa/Makefile
@@ -0,0 +1,25 @@
+BINARY=itoa
+
+CFILES=$(wildcard *.c)
+TESTDIR=./tests/
+TESTS=$(wildcard $(TESTDIR)*.tin)
+TEST_RESULTS=$(patsubst %.tin,%.res,$(TESTS))
+
+CC=gcc
+CFLAGS=-Wall -Wextra -Werror -ggdb -std=c89
+
+
+all: $(BINARY)
+
+$(BINARY): $(CFILES)
+	$(CC) $(CFLAGS) -o $@ $^
+
+check: $(TEST_RESULTS)
+
+%.res: %.tin
+	@./$(BINARY) <$? >$@ult
+	@diff --color=always --text $@ult $(patsubst %.tin,%.tout,$?)
+
+clean:
+	rm -f $(BINARY)
+	rm -f $(TESTDIR)*.result
diff --git a/chapter_3.control_flow/3_04.itoa/main.c b/chapter_3.control_flow/3_04.itoa/main.c
new file mode 100644
index 0000000..a8df3f6
--- /dev/null
+++ b/chapter_3.control_flow/3_04.itoa/main.c
@@ -0,0 +1,63 @@
+# include <stdio.h>
+# include <limits.h>
+# include <string.h>
+
+# define MAXLEN 128
+
+void itoa (int n, char s[]);
+void reverse (char s[]);
+void test_itoa (int n);
+
+
+int main()
+{
+  test_itoa(0);
+  test_itoa(578678);
+  test_itoa(-98173);
+  test_itoa(INT_MAX);
+  test_itoa(INT_MIN+1);
+  test_itoa(INT_MIN);
+  return 0;
+}
+
+
+void test_itoa (int n)
+{
+  char s[MAXLEN];
+
+  itoa(n, s);
+  printf("%d: %s\n", n, s);
+}
+
+
+void itoa (int n, char s[])
+{
+  int i, sign;
+  unsigned int nn;
+
+  if ((sign = n) < 0) { /* record sign */
+    nn = -n;            /* make n positive */
+  } else {
+    nn = n;
+  }
+  i = 0;
+  do { /* generate digits in reverse order */
+    s[i++] = nn % 10 + '0'; /* get next digit */
+  } while ((nn /= 10) > 0); /* delete it */
+  if (sign < 0)
+    s[i++] = '-';
+  s[i] = '\0';
+  reverse(s); /* reverse digits order */
+}
+
+
+void reverse (char s[])
+{
+  int c, i, j;
+
+  for (i = 0, j = strlen(s)-1; i < j; i++, j--) {
+    c = s[i];
+    s[i] = s[j];
+    s[j] = c;
+  }
+}
diff --git a/chapter_3.control_flow/3_04.itoa/tests/t0.tin b/chapter_3.control_flow/3_04.itoa/tests/t0.tin
new file mode 100644
index 0000000..e69de29
diff --git a/chapter_3.control_flow/3_04.itoa/tests/t0.tout b/chapter_3.control_flow/3_04.itoa/tests/t0.tout
new file mode 100644
index 0000000..ab58b33
--- /dev/null
+++ b/chapter_3.control_flow/3_04.itoa/tests/t0.tout
@@ -0,0 +1,6 @@
+0: 0
+578678: 578678
+-98173: -98173
+2147483647: 2147483647
+-2147483647: -2147483647
+-2147483648: -2147483648