Tutorial appendix

tutorial/address_in.c

+#include <stdlib.h>
+#include <stdio.h>
+
+void double_in(int *in){
+    *in *= 2;
+}
+
+int main(){
+    int x= 10;
+    double_in(&x);
+    printf("x is now %i.\n", x);
+}

tutorial/assert.c

+#include <assert.h>
+
+int main(){
+    int list[100];
+    int *list2 = list;    //Declares list2 as a pointer-to-int,
+                          //pointing to the same block of memory list points to.
+
+    *list2 = 7;           //list2 is a pointer-to-int, so *list2 is an int.
+
+    assert(list[0] == 7);
+}

tutorial/divisions.c

+#include <stdio.h>
+
+int main(){
+    printf("3./5=%g\n", 3./5);
+    printf("3/5=%i\n", 3/5);
+    printf("3%%5=%i\n", 3%5);
+}

tutorial/do_while.c

+#include <stdio.h>
+
+void loops(int max){
+    int i=0;
+    do {
+        printf("Hello #%i\n", i);
+        i++;
+    } while (i < max);      //Note the semicolon.
+
+}
+
+int main(){
+    loops(3); //prints three greetings
+    loops(0); //prints one greeting
+}

tutorial/error_print.c

+#include <stdio.h>
+
+void error_print(FILE *ef, int error_code, char *msg){
+    fprintf(ef, "Error #%i occurred: %s.\n", error_code, msg);
+}
+
+int main(){
+    FILE *error_file = fopen("example_error_file", "w"); //open for writing
+    error_print(error_file, 37, "Out of karma");
+}

tutorial/for_loop.c

+#include <stdio.h>
+
+int main(){
+    for (int i=0; i < 10; i++){
+        printf("Hello #%i\n", i);
+    }
+}

tutorial/for_loop2.c

+#include <stdio.h>
+
+int main(){
+    for (int i=0; i < 10; i++) printf("Hello #%i\n", i);
+}

tutorial/hello.c

+#include <stdio.h>
+
+int main(){
+    printf("Hello, world.\n");
+}

tutorial/if_else.c

+#include <stdio.h>
+
+int main(){
+    if (6 == 9)
+        printf("Six is nine.\n");
+
+    int x=3;
+    if (x==1)
+        printf("I found x; it is one.\n");
+    else if (x==2)
+        printf("x is definitely two.\n");
+    else
+        printf("x is neither one nor two.\n");
+}

tutorial/item_seven.c

+#include <stdio.h>
+
+int intlist[10];
+
+int main(){
+    int len=20;
+    char string[len];
+
+    intlist[7] = 7;
+    snprintf(string, 20, "Item seven is %i.", intlist[7]);
+    printf("string says: <<%s>>\n", string);
+}

tutorial/makefile

+CFLAGS=-g -Wall -std=gnu11 -O3
+LDLIBS=-lm

tutorial/manual_memory.c

+#include <stdlib.h> //malloc and free
+#include <stdio.h>
+
+int main(){
+    int *intspace = malloc(3000*sizeof(int));
+    for (int i=0; i < 3000; i++)
+        intspace[i] = i;
+
+    FILE *cf = fopen("counter_file", "w");
+    for (int i=0; i < 3000; i++)
+        fprintf(cf, "%i\n", intspace[i]);
+
+    free(intspace);
+    fclose(cf);
+}

tutorial/pointer_in.c

+#include <stdlib.h>
+#include <stdio.h>
+
+void double_in(int *in){
+    *in *= 2;
+}
+
+int main(){
+    int *x= malloc(sizeof(int));
+    *x= 10;
+    double_in(x);
+    printf("x now points to %i.\n", *x);
+}

tutorial/ratio_s.c

+#include <stdio.h>
+
+typedef struct {
+    int numerator, denominator;
+    double value;
+} ratio_s;
+
+ratio_s new_ratio(int num, int den){
+    return (ratio_s){.numerator=num, .denominator=den, .value=num/(double)den};
+}
+
+void print_ratio(ratio_s r){
+    printf("%i/%i = %g\n", r.numerator, r.denominator, r.value);
+}
+
+ratio_s ratio_add(ratio_s left, ratio_s right){
+    return (ratio_s){
+        .numerator=left.numerator*right.denominator
+                     + right.numerator*left.denominator,
+        .denominator=left.denominator * right.denominator,
+        .value=left.value + right.value
+    };
+}
+
+int main(){
+    ratio_s twothirds= new_ratio(2, 3);
+    ratio_s aquarter= new_ratio(1, 4);
+    print_ratio(twothirds);
+    print_ratio(aquarter);
+    print_ratio(ratio_add(twothirds, aquarter));
+}

tutorial/sizeof.c

+#include <stdio.h>
+
+typedef struct {
+    int numerator, denominator;
+    double value;
+} ratio_s;
+
+int main(){
+    printf("size of two ints: %zu\n", 2*sizeof(int));
+    printf("size of two ints: %zu\n", sizeof(int[2]));
+    printf("size of a double: %zu\n", sizeof(double));
+    printf("size of a ratio_s struct: %zu\n", sizeof(ratio_s));
+}

tutorial/sqrt.c

+#include <math.h>   //The square root function is declared here.
+#include <stdio.h>
+
+int main(){
+    double x = 49;
+    printf("The truncated square root of x is %g.\n",
+                                    x > 0 ? sqrt(x) : 0);
+}

tutorial/ten_pi.c

+#include <stdio.h>
+
+int main(){
+    double pi= 3.14159265; //POSIX defines the constant M_PI in math.h, by the way.
+    int count= 10;
+    printf("%g times %i = %g.\n", pi, count, pi*count);
+}

tutorial/while.c

+#include <stdio.h>
+
+int main(){
+    int i=0;
+    while (i < 10){
+        printf("Hello #%i\n", i);
+        i++;
+    }
+}