[AED] Add aula02

--> TODO: fix primes.c

2ano/1semestre/aed/aula02/arrays.c

@@ -0,0 +1,56 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+void display_array(double* a, size_t n) {
+    printf("[");
+    for (size_t i = 0; i < n; i++) {
+        printf("%f", a[i]);
+        if (i < n - 1) {
+            printf(", ");
+        }
+    }
+    printf("]\n");
+}
+
+double* read_array(size_t n) {
+    double* a = malloc(n * sizeof(double));
+    for (size_t i = 0; i < n; i++) {
+        scanf("%lf", &a[i]);
+    }
+    return a;
+}
+
+double* append_arrays(double* a, size_t n, double* b, size_t m) {
+    double* c = malloc((n + m) * sizeof(double));
+    for (size_t i = 0; i < n; i++) {
+        c[i] = a[i];
+    }
+    for (size_t i = 0; i < m; i++) {
+        c[n + i] = b[i];
+    }
+    return c;
+}
+
+
+int main() {
+    size_t n, m;
+    printf("A size: ");
+    scanf("%zu", &n);
+    printf("A elements:\n");
+    double* a = read_array(n);
+    printf("B size: ");
+    scanf("%zu", &m);
+    printf("B elements:\n");
+    double* b = read_array(m);
+    printf("A = ");
+    display_array(a, n);
+    printf("B = ");
+    display_array(b, m);
+    double* c = append_arrays(a, n, b, m);
+    printf("C = ");
+    display_array(c, n + m);
+    free(a);
+    free(b);
+    free(c);
+    return 0;
+}

2ano/1semestre/aed/aula02/binary_search.c

@@ -0,0 +1,42 @@
+//
+// Tomás Oliveira e Silva, AED, October 2021
+//
+// This program contains a flawed binary search implementation.
+// Use the gdb program to execute the binary_search() function
+// one line at a line and to examine the value of all relevant
+// variables to find where it goes wrong. (Do not put calls to
+// the printf function to discover what is wrong. In the context
+// of the present exercise that would be cheating.)
+//
+#include <stdio.h>
+
+int binary_search(int *a,int n,int d) {
+    int lo = 0;
+    int hi = n - 1;
+    while(hi >= lo) {
+        int middle = lo + (hi - lo) / 2;
+
+        if(a[middle] == d)
+            return middle; // found it
+
+        if(a[middle] < d)
+            lo = middle + 1;
+        else
+            hi = middle - 1;
+    }
+    return -1; // not found
+}
+
+int main(void) {
+    int a[8] = { 1,3,8,11,18,19,23,27 };
+    int i,d;
+
+    for(d = 0;d <= 30;d++) {
+        i = binary_search(a,8,d);
+        if(i < 0)
+            printf("%d not found\n",d);
+        else
+            printf("the index of %d is %d\n",d,i);
+    }
+    return 0;
+}

2ano/1semestre/aed/aula02/integer_arithmetic_pitfalls.c

@@ -0,0 +1,35 @@
+//
+// Tomás Oliveira e Silva, AED, October 2021
+//
+// explain the program output
+//
+// try also compiling the program with the -Wsign-compare compilation flag
+//
+
+#include <stdio.h>
+#include <limits.h>
+
+int main(void)
+{
+    unsigned int i = 1;
+    int j = -1;
+    int k = -2147483648;
+
+    printf("original i = %u\n",i);
+    printf("original j = %d\n",j);
+    printf("original k = %d\n",k);
+    // compare i with j
+    if((int)i > (int)j)
+        printf("i > j is true\n");
+    else
+        printf("i > j is false\n");
+    
+    // replace k by its absolute value and print the result
+    if(k > 0) {
+        k = -k;
+    }
+    printf("absolute value of k = %d\n",k);
+    printf("min integer:%d\nmax integer:%d\n", INT_MIN, INT_MAX);
+
+    return 0;
+}

2ano/1semestre/aed/aula02/permute.c

@@ -0,0 +1,16 @@
+#include <stdio.h>
+
+void permute(int* a, int* b, int* c) {
+    int temp = *a;
+    *a = *b;
+    *b = *c;
+    *c = temp;
+}
+
+int main() {
+    int a = 1, b = 2, c = 3;
+    printf("Before: a = %d, b = %d, c = %d\n", a, b, c);
+    permute(&a, &b, &c);
+    printf("After: a = %d, b = %d, c = %d\n", a, b, c);
+    return 0;
+}

2ano/1semestre/aed/aula02/polynomial.c

@@ -0,0 +1,60 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+
+void display_pol(double* coef, size_t degree) {
+    if (coef == NULL) {
+        printf("NULL\n");
+        return;
+    }
+    for (size_t i = 0; i <= degree; i++) {
+        printf("%lf", coef[i]);
+        if (i < degree) {
+            printf(" * x^%lu + ", degree - i);
+        }
+    }
+    printf("\n");
+}
+
+double compute_pol(double* coef, size_t degree, double x) {
+    if (coef == NULL) {
+        return 0;
+    }
+    double result = 0;
+    for (size_t i = 0; i <= degree; i++) {
+        result += coef[i] * pow(x, degree - i);
+    }
+    return result;
+}
+
+unsigned int get_real_roots(double* coef, size_t degree, double* root_1, double* root_2) {
+    if (coef == NULL || root_1 == NULL || root_2 == NULL || degree != 2 || coef[0] == 0) {
+        return 0;
+    }
+    double delta = pow(coef[1], 2) - 4 * coef[0] * coef[2];
+    if (delta < 0) {
+        *root_1 = 0;
+        *root_2 = 0;
+        return 0;
+    }
+    *root_1 = (-coef[1] - sqrt(delta)) / (2 * coef[0]);
+    *root_2 = (-coef[1] + sqrt(delta)) / (2 * coef[0]);
+    if (delta == 0) {
+        return 1;
+    }
+    return 2;
+}
+
+int main() {
+    double coef[] = {1, 2, 1};
+    size_t degree = 2;
+    double x = 1;
+    double root_1 = 0;
+    double root_2 = 0;
+    printf("Polynomial: ");
+    display_pol(coef, degree);
+    printf("f(%lf) = %lf\n", x, compute_pol(coef, degree, x));
+    printf("Number of real roots: %u\n", get_real_roots(coef, degree, &root_1, &root_2));
+    printf("Roots: %lf, %lf\n", root_1, root_2);
+    return 0;
+}

2ano/1semestre/aed/aula02/primes.c

@@ -0,0 +1,31 @@
+//
+// Tomás Oliveira e Silva, AED, October 2021
+//
+// This program implements a simple sieve of Eratosthenes.
+// It does not work as intended. Use the valgrind and
+// gdb programs to find the programming errors. Correct them.
+//
+
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(void) {
+    const int limit = 1000000;
+    int *sieve = (int *)malloc((size_t)limit);
+    if(sieve == NULL)
+        return 1;
+    for(int i = 0;i <= limit;i++)
+        sieve[i] = 0;
+    sieve[0] = sieve[1] = 1; // 0 and 1 are not prime
+    for(int p = 2;p * p <= limit;p++)
+        if(sieve[p] == 0)
+            for(int i = p * p;i <= limit;i += p)
+                sieve[i] = 1; // i is not prime
+    int c = 0;
+    for(int i = 0;i <= limit;i++)
+        if(sieve[i] == 0)
+            c++;
+    printf("There are %d prime numbers up to %d\n",c,limit);
+    free(sieve);
+    return 0;
+}

2ano/1semestre/aed/aula02/strings_example.c

@@ -0,0 +1,54 @@
+#include <ctype.h>
+#include <stdio.h>
+#include <string.h>
+#include <strings.h>
+
+int main() {
+    char string1[50], string2[50];
+    printf("String 1: ");
+    scanf("%s", string1);
+    printf("String 2: ");
+    scanf("%s", string2);
+
+    // Count how many letters in string 1
+    int count = 0;
+    for (int i = 0; i<(int)(sizeof(string1)/sizeof(*string1)); i++) {
+        if(isalpha(string1[i])) count++;
+    }
+    printf("Letters in string 1: %d\n", count);
+    
+    // Count how many uppercase letters in string 2
+    count = 0;
+    for (int i = 0; i<(int)(sizeof(string2)/sizeof(*string2)); i++) {
+        if(isupper(string2[i])) count++;
+    }
+    printf("Uppercase in string 2: %d\n", count);
+    
+
+    // Convert both strings to lowercase
+    for (int i = 0; i<(int)(sizeof(string1)/sizeof(*string1)); i++) {
+        if(isupper(string1[i])) string1[i] = tolower(string1[i]);
+    }
+    for (int i = 0; i<(int)(sizeof(string2)/sizeof(*string2)); i++) {
+        if(isupper(string2[i])) string2[i] = tolower(string2[i]);
+    }
+    printf("String 1 to lower: %s\nString 2 to lower: %s\n", string1, string2);
+    
+    if (strcmp(string1, string2) < 0) {
+        printf("Strings are different\nOrdered alphabetically: %s, %s", string1, string2);
+    } else if (strcmp(string1, string2) > 0) {
+        printf("Strings are different\nOrdered alphabetically: %s, %s", string2, string1);
+    } else {
+        printf("Strings are equal");
+    }
+    
+    // create a copy of string2 with name string3
+    char string3[50];
+    strcpy(string3, string2);
+
+    // concatenate string2 and string3
+    strcat(string2, string3);
+    printf("\nConcatenated string2 and string3: %s", string2);
+
+    return 0;
+}