For Windows users:

https://www.ucalgary.ca/cpsc/tech/services/computing_resources

Use PuTTY: https://www.ucalgary.ca/cpsc/tech/services/putty_usage

#include <stdio.h> // Include functions from the standard I/O library

// Define the main function
int main(int argc, char *argv[]) // argc: number of arguments passed
                                 // argv: array to (pointer to) argument text
{
    printf("Hello World!\n");    // prints hello world

    return 0;                    // returns 0 (error code 0 = no error)
}

#include <stdio.h>

int main(int argc, char *argv[])
{
    char name[256];
    int age;

    printf("Please enter your name:\n");
    scanf("%s", name); 

    printf("Please enter your age: \n");
    scanf("%d", &age); // & is the "address of" operator

    printf("Hello %s, you are %d years younger than I am\n", name, 27 - age);
}

We'll talk about unsigned types later on...

char is short for character, a string is a list or array of characters

Format strings are powerful but complicated.

#include <stdio.h> // Include functions from the standard I/O library

int main(int argc, char *argv[]) 
{
    int array[16]; // Make an array of 16 elements
    int example = 123456;

    // we can assign elements of the array
    array[0] = 10;

    printf("Array[0] = %d\n", array[0]);

    // in a loop
    for(int i = 0; i < 16; i++) {
        array[i] = i;
    } 

    for(int i = 0; i < 16; i++) {
        printf("Array[%d] = %d\n", i, array[i]);
    }

    printf("Let's try something different...\n");
    printf("Array[17] = %d?\n", array[17]);
    array[17] = 0;

    printf("example = %d\n", example);
}

#include <stdio.h> // Include functions from the standard I/O library

int main(int argc, char *argv[]) 
{
    int *array = calloc(16, sizeof(int)); // Make an array of 16 elements on the /heap/
    int example = 123456;

    // we can assign elements of the array
    array[0] = 10;

    printf("Array[0] = %d\n", array[0]);

    // in a loop
    for(int i = 0; i < 16; i++) {
        array[i] = i;
    } 

    for(int i = 0; i < 16; i++) {
        printf("Array[%d] = %d\n", i, array[i]);
    }

    printf("Let's try something different...\n");
    printf("Array[17] = %d?\n", array[17]);
    array[17] = 0;

    printf("example = %d\n", example);
    free(array); // need to clean up memory we allocated on the heap
}

#include <stdio.h> // Include functions from the standard I/O library

int main(int argc, char *argv[]) 
{
    char message[8];

    message[0] = 'H';
    message[1] = 'e';
    message[2] = 'l';
    message[3] = 'l';
    message[4] = 'o';
    message[5] = '!';
    message[6] = '\n';
    message[7] = 0; // 0 means "end of string", it's the NULL character

    puts(message); // Here's a new function puts or put string
}

#include <stdio.h> // Include functions from the standard I/O library

int main(int argc, char *argv[]) 
{
    char message[8];

    message[0] = 72;
    message[1] = 101;
    message[2] = 108;
    message[3] = 108;
    message[4] = 110;
    message[5] = 31;
    message[6] = 10;
    message[7] = 0;

    puts(message); 
}

#include <stdio.h> // Include functions from the standard I/O library

int main(int argc, char *argv[]) 
{
    char message[256], dest_buffer[256];
    printf("Enter a word\n");
    scanf("%s", message);

    // strlen(str) returns the length of a string
    printf("Your message %s, is %d characters long", message, strlen(message));

    // strcmp compares two strings, returns 0 if they're identical
    // "Hello" == message does not work in C
    if(strcmp("Hello", message) == 0) {
        printf("I see you're just starting comp sci.\n");
    } 

    strcpy(dest_buffer, message);
    dest_buffer[0] = 'X';

    printf("This was your original message:\n%s\n", message);
    printf("This is the copied message:\n%s\n", dest_buffer);
}

#include <stdio.h> // Include functions from the standard I/O library

int main(int argc, char *argv[]) 
{
    int *pointer = NULL; // Set the pointer to point at 0;
    
    int a_value = 100;

    // Doing the following will crash your program
    printf("Value at pointer = %d\n", *pointer); // * means "get value at pointer" here
                                                 // it's also known as dereferencing
                                                 // synonymous to pointer[0]

    pointer = &a_value; // here, & means "get the address value of the variable"
                        // it's known as the reference operator

    printf("Value at pointer = %d\n", *pointer);

    printf("pointer[0] = %d\n", pointer[0]);
}

• Some simple ARMv8 assembly (if statements, loops)
• Debugging