3.5

Author: Heatwave

chapter-3-control-flow/5.atoi.c

@@ -0,0 +1,31 @@
+#include <ctype.h>
+#include <stdio.h>
+
+main()
+{
+	printf("%d\n", atoi("123"));
+	printf("%d\n", atoi("+1"));
+	printf("%d\n", atoi("-0"));
+	printf("%d\n", atoi("-123"));
+	printf("%d\n", atoi("asd345"));
+	printf("%d\n", atoi("789asd345"));
+}
+
+int atoi(char s[])
+{
+	int i, n, sign;
+
+	for (i = 0; isspace(s[i]); i++)
+		;
+
+	sign = (s[i] == '-') ? -1 : 1;
+
+	if (s[i] == '+' || s[i] == '-')
+		i++;
+
+	for (n = 0; isdigit(s[i]); i++)
+		n = 10 * n + (s[i] - '0');
+	
+	return sign * n;
+}
+

chapter-3-control-flow/6.shellsort.c

@@ -0,0 +1,36 @@
+#include <stdio.h>
+
+void shellsort(int [], int);
+void printArr(int [], int);
+
+main()
+{
+	int len = 12;
+	int v[] = {11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0};
+	printArr(v, len);
+	shellsort(v, len);
+	printArr(v, len);
+}
+
+// sort v[0]...v[n-1] into increasing order
+void shellsort(int v[], int n)
+{
+	int gap, i, j, temp;
+
+	for (gap = n / 2; gap > 0; gap /= 2)
+		for (i = gap; i < n; i++)
+			for (j = i - gap; j >= 0 && v[j] > v [j + gap]; j -= gap) {
+				printf("gap: %d, i: %d, j: %d, j+gap: %d\n", gap, i, j, j+gap);
+				temp = v[j];
+				v[j] = v[j+gap];
+				v[j+gap] = temp;
+			}
+}
+
+void printArr(int v[], int len)
+{
+	int i;
+	for (i = 0; i < len; i++)
+		printf("%d ", v[i]);
+	printf("\n");
+}

chapter-3-control-flow/7.reverse.c

@@ -0,0 +1,22 @@
+#include <stdio.h>
+#include <string.h>
+
+void reverse(char[]);
+
+main()
+{
+	char a[] = "Hello, World!";
+	reverse(a);
+	printf("%s\n", a);
+}
+
+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;
+	}
+}

chapter-3-control-flow/8.expand.c

@@ -0,0 +1,42 @@
+#include <stdio.h>
+
+#define MAX_LEN 1024
+
+void expand(char s1[], char s2[]);
+
+main()
+{
+	char s1[] = "-a-z-A-Z-0-9-asd-5-5-5-9a-ZZ-A-G-N-T-Z";
+	char s2[MAX_LEN];
+	expand(s1, s2);
+	printf("%s\n", s2);
+
+	char s[] = "-a-z 0-9 a-d-f -0-2 some text 1-1 WITH CAPITALS! 0-0 5-3 -";
+	char t[MAX_LEN];
+	expand(s, t);
+	printf("%s\n", t);
+}
+
+void expand(char s1[], char s2[])
+{
+	int i, j, k;
+
+	for (i = 0, j = 0; s1[i] != '\0'; i++) {
+		if (s1[i] == '-' && i > 0 && s1[i+1] != '\0') {
+			int p = s1[i-1];
+			int n = s1[i+1];
+			if (p < n && 
+				((p >= 'a' && n <= 'z') || (p >= 'A' && n <= 'Z') || (p >= '0' && n <= '9'))
+			) {
+				for (k = p + 1; k < n; k++)
+					s2[j++] = k;
+			} else {
+				s2[j++] = s1[i];
+			}
+		} else {
+			s2[j++] = s1[i];
+		}
+	}
+
+	s2[j] = '\0';
+}