initial commit

1_n_a_factorial.c

@@ -0,0 +1,14 @@
+#include <stdio.h>
+#define N 10
+
+int main() {
+	int i, solution = 1;
+
+	for (i = 1; i <= N; i++) { 
+		solution *= i;
+		printf("The factorial of %d is:\t%d\n", i, solution);
+	}
+
+	return 0;
+}
+

1_n_b_ascii.c

@@ -0,0 +1,11 @@
+#include <stdio.h>
+
+int main() {
+	char letter = 'A';
+	printf("Letter\tDec in ASCII-Table\n");
+
+	do printf("%c\t\t\t%d\n", letter, letter);
+	while (letter++ <= 'Z');
+
+	return 0;
+}

1_p_a_kanten.c

@@ -0,0 +1,16 @@
+#include <stdio.h>
+
+#define DELTA 1
+#define MAX 10
+
+int main() {
+	int umfang, flaeche, a = 0;
+	do {
+		umfang = 4*a;
+		flaeche = a*a;
+		printf("Seitenlaenge = %d cm \t=> Fläche = %d cm^2 \tund Umfang = %d cm\n", a, flaeche, umfang);
+		a = a + DELTA;
+	} while (a <= MAX);
+
+	return 0;
+}

1_v_a_square.c

@@ -0,0 +1,16 @@
+#include <stdio.h>
+#include <math.h>
+
+#define MAX 10
+
+int main() {
+	int n = 1;
+	printf("Liste der ersten %d Quadratzahlen:\n", MAX);
+
+	while (n <= MAX) {
+		printf("%d\n", (int) pow(n, 2));
+		n += 1;
+	}
+
+	return 0;
+}

2_p_b_raten.c

@@ -0,0 +1,27 @@
+#include <stdio.h>
+
+#define MAX 3
+#define FIND 'z'
+
+int main() {
+	int anzahl;
+	char versuch;
+
+	for(anzahl=1; anzahl <= 3; anzahl++) {
+		printf("Enter letter:\t");
+		scanf(" %c", &versuch); 
+
+		if (versuch == FIND) {
+			printf("Super!\n");
+			return 0;
+		}
+		else {
+			printf("Wrong! Next try!\n");
+		}
+	}
+	printf("You missed all your chances!\n");
+
+	return -1;
+}
+
+

2_p_c_tree.c

@@ -0,0 +1,14 @@
+#include <stdio.h>
+
+int main() {
+	int level;
+	for (level = 1; level < 7; level++) {
+		int column;
+		for (column = 1; column <= level; column++) {
+			printf("*");
+		}
+		printf("\n");
+	}
+
+	return 0;
+}

2_p_d_einXeins.c

@@ -0,0 +1,14 @@
+#include <stdio.h>
+
+int main() {
+	int a, b;
+
+	for (a = 0; a <= 10; a++) {
+		for (b = 0; b <= 10; b++) {
+			printf("%d\t", a*b);
+		}
+		printf("\n");
+	}
+
+	return 0;
+}

2_v_b_logic.c

@@ -0,0 +1,16 @@
+#include <stdio.h>
+
+int main() {
+	/* table header */
+	printf("a\tb\t!a\ta || b\ta && b\ta^b\n");
+	printf("--------------------------------------------\n");
+
+	int a, b;
+	for (a= 0; a < 2; a++) {
+		for (b = 0; b < 2; b++) {
+			printf("%d\t%d\t%d\t%d\t%d\t%d\n", a, b, !a, a || b, a && b, a^b);
+		}
+	}
+
+	return 0;
+}

3_n_a_xor_encryption.c

@@ -0,0 +1 @@
+#include <stdio.h>
#include <string.h>

#define MAX_LENGTH 31 // 30 characters + '\0' termination
#define SALT 15

int main() {
	char input[MAX_LENGTH];
	int offset = 0;
	char character;

	// prompt for input
	printf("Please enter message: ");
	while (offset + 1 < MAX_LENGTH && (character = getchar()) != '\n') {
		input[offset++] = character;
	}
	input[offset] = '\0';

	// encrypt message
	for (offset = 0; offset < strlen(input); offset++) {
		input[offset] ^= SALT;
	}
	printf("Encrypted message: %s\n", input);

	// decrypt message
	for (offset = 0; offset < strlen(input); offset++) {
		input[offset] ^= SALT;
	}
	printf("Decrypted message: %s\n", input);

	return 0;
}

3_n_b_scalarm.c

@@ -0,0 +1,36 @@
+#include <stdio.h>
+#include <math.h>
+
+#define DIMENSION 2
+
+int main() {
+	float matrix[DIMENSION][DIMENSION] = {
+		{2.1, 3.0},
+		{4.2, 3.5}
+	};
+
+	float scalar;
+	int i, j;
+
+	printf("Matrix before operation:\n");
+	for (i = 0; i < DIMENSION; i++) {
+		for (j = 0; j < DIMENSION; j++) {
+			printf("%.3f\t", matrix[i][j]);
+		}
+		printf("\n");
+	}
+
+	printf("Please enter a scalar to multiply with: ");
+	scanf("%f", &scalar);
+
+	printf("Matrix after operation:\n");
+	for (i = 0; i < DIMENSION; i++) {
+		for (j = 0; j < DIMENSION; j++) {
+			matrix[i][j] *= scalar;
+			printf("%.3f\t", matrix[i][j]);
+		}
+		printf("\n");
+	}
+
+	return 0;
+}

3_n_c_userdb.c

@@ -0,0 +1,50 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define MAX_ACCOUNTS 10
+#define BUFFER_SIZE 256
+
+typedef struct {
+	char active;
+	char * name;
+	char * password;
+} user;
+
+int main() {
+	user users[MAX_ACCOUNTS];
+	char input_buffer[BUFFER_SIZE];
+	int count, offset;
+
+	for (offset = 0, count = 0; offset < MAX_ACCOUNTS; offset++, count++) {
+		printf("Should this user be activated? (0/1/-1): ");  // -1 for break input
+		fgets(input_buffer, BUFFER_SIZE, stdin);
+		users[offset].active = atoi(input_buffer);
+		if (users[offset].active == -1) {
+			break;
+		}
+
+		printf("Please enter a username: ");
+		fgets(input_buffer, BUFFER_SIZE, stdin);
+		users[offset].name = malloc(strlen(input_buffer));
+		strncpy(users[offset].name, input_buffer, strlen(input_buffer)-1);
+
+		printf("Please enter a password: ");
+		fgets(input_buffer, BUFFER_SIZE, stdin);
+		users[offset].password = malloc(strlen(input_buffer));
+		strncpy(users[offset].password, input_buffer, strlen(input_buffer)-1);
+	}
+
+	if (count > 0) {
+		/* table header */
+		printf("No.\tName\t\t\tPassword\t\tActive?\n");
+
+		for (offset = 0; offset < count; offset++) {
+			printf("%d\t%-24s%-24s%s\n", offset+1, users[offset].name, users[offset].password, users[offset].active ? "yes" : "no");
+		}
+		return 0;
+	}
+	else {
+		return -1;
+	}
+}

3_p_a_zaehlen.c

@@ -0,0 +1,17 @@
+#include <stdio.h>
+
+#define NEEDLE 'e'
+
+int main() {
+	int counter = 0;
+	char character;
+
+	printf("Please enter a message: ");
+	while ((character = getchar()) != '\n') {
+		if (character == NEEDLE) counter++;
+	}
+
+	printf("Found '%c' %d times\n", NEEDLE, counter);
+
+	return 0;
+}

3_p_b_transponieren.c

@@ -0,0 +1,31 @@
+#include <stdio.h>
+
+#define DIMENSION 4
+
+int main() {
+	int matrix[DIMENSION][DIMENSION] = {
+		{1,  2,  3,  4},
+		{5,  6,  7,  8},
+		{9,  10, 11, 12},
+		{13, 14, 15, 16}
+	};
+
+	int temp, x, y;
+
+	for (x = 0; x < DIMENSION; x++) {
+		for (y = 0; y < x; y++) {
+			temp = matrix[x][y];
+			matrix[x][y] = matrix[y][x];
+			matrix[y][x] = temp;
+		}
+	}
+
+	for (x = 0; x < DIMENSION; x++) {
+		for (y = 0; y < DIMENSION; y++) {
+			printf("%d\t", matrix[x][y]);
+		}
+		printf("\n");
+	}
+
+	return 0;
+}

3_p_c_parteien.c

@@ -0,0 +1,36 @@
+#include <stdio.h>
+
+#define MAX_SEATS 200
+#define THRESHOLD 5
+
+typedef struct {
+	char * name;
+	float percentage;
+	int seats;
+} party;
+
+int main() {
+	party parties[] = {
+		{"MFG", 40.3},
+		{"Mitte", 55.0},
+		{"EBS", 4.7}
+	};
+
+	int i;
+	const int party_count = sizeof parties / sizeof (party);
+	float significant_percentage = 0;
+
+	for (i = 0; i < party_count; i++) {
+		if (parties[i].percentage >= THRESHOLD) {
+			significant_percentage += parties[i].percentage;
+		}
+	}
+
+	for (i = 0; i < party_count; i++) {
+		parties[i].seats = parties[i].percentage >= THRESHOLD ? MAX_SEATS * (parties[i].percentage / significant_percentage) : 0;
+		printf("%s\t%.1f%%\t(%d Sitze)\n", parties[i].name, parties[i].percentage, parties[i].seats);
+	}
+
+	return 0;
+
+}

Makefile

@@ -0,0 +1,12 @@
+SRCS = $(wildcard *.c)
+PROGS = $(patsubst %.c,%,$(SRCS))
+
+CFLAGS += -g -Wall -O0
+
+all: $(PROGS)
+
+%: %.c
+	$(CC) $(CFLAGS)  -o $@ $<
+
+clean:
+	rm -f *.o *.save $(PROGS)

README

@@ -0,0 +1,3 @@
+Lösungen zu den Aufgaben der KGÜ Information 1 im WS 2010/11 an der RWTH Aachen
+
+Benutze "make all" um alle Programme auf einmal zu kompilieren