2019-10-03 in class

myscanf.c

@@ -0,0 +1,50 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <ctype.h>
+#include <limits.h>
+
+char next_sign_char();
+
+inline char next_sign_char() {
+	char c;
+	while (isspace(c = getchar()));
+	return c;
+}
+
+int read_int(int* p) {
+	int i = 0;
+	bool pos = true;
+
+	char c = next_sign_char();
+
+	if (c == '-' || c == '+') {
+		pos = c == '+';
+	} else if (!isdigit(c)) {
+		return 0;
+	} else {
+		i = c - '0';
+	}
+
+	while ((c = getchar()) != EOF && c != '\n' && c != ' ') {
+		if (!isdigit(c)) return 0;
+		int digit = c - '0';
+		if ((pos && i > (MAX_INT - digit) / 10) ||
+			(!pos && i > (-1 * MIN_INT - digit) / 10)) {
+			break;
+		}
+		i *= 10;
+		i += c - '0';
+	}
+
+	*p = pos ? i : -i;
+	return 1;
+}
+
+
+
+int main() {
+	int a;
+	read_int(&a);
+	printf("%d", a);
+}

revargs.c

@@ -0,0 +1,23 @@
+// vim: set ts=4 sw=4 et tw=80:
+
+#include <stdio.h>
+#include <string.h>
+#include <stdbool.h>
+
+bool compare_reverse(char* s1, char* s2) {
+	const size_t len = strlen(s1);
+	if (len != strlen(s2))
+		return false;
+	for (size_t i = 0; i < len; i++)
+		if (s1[i] != s2[len - 1 - i])
+			return false;
+	return true;
+}
+
+
+int main (const int argc, char** argv) {
+	for (int i = 1; i < argc - 1; i++)
+		for (int j = i + 1; j < argc; j++)
+			if (compare_reverse(argv[i], argv[j]))
+				printf("%s %s\n", argv[i], argv[j]);
+}