[SPCA] Continue summary

semester3/spca/code-examples/00_c/00_basics/00_intro.c

@@ -0,0 +1,17 @@
+// This is a line comment
+/* this is a block comment */
+#include "01_func.h" // Relative import
+
+int i = 0; // This allocates an integer on the stack
+
+int main( int argc, char *argv[] ) {
+    // This is the function body of a function (here the main function)
+    // which serves as the entrypoint to the program in C and has arguments
+    printf( "Argc: %d\n", argc );    // Number of arguments passed, always >= 1
+                                     // (first argument is the executable name)
+    for ( int i = 0; i < argc; i++ ) // For loop just like any other sane programming language
+        printf( "Arg %d: %s\n", i, argv[ i ] ); // Outputs the i-th argument from CLI
+
+    get_user_input_int( "Select a number" ); // Function calls as in any other language
+    return 0;                                // Return a POSIX exit code
+}

semester3/spca/code-examples/00_c/00_basics/01_func.c

@@ -0,0 +1,43 @@
+#include "01_func.h"
+#include <stdio.h>
+
+int get_user_input_int( char prompt[] ) {
+    int input_data;
+    printf( "%s", prompt );           // Always wrap strings like this for printf
+    scanf( "%d", &input_data );       // Get user input from CLI
+    int input_data_copy = input_data; // Value copied
+
+    // If statements just like any other language
+    if ( input_data )
+        printf( "Not 0" );
+    else
+        printf( "Input is zero" );
+
+    // Switch statements just like in any other language
+    switch ( input_data ) {
+        case 5:
+            printf( "You win!" );
+            break; // Doesn't fall through
+        case 6:
+            printf( "You were close" ); // Falls through
+        default:
+            printf( "No win" ); // Case for any not covered input
+    }
+
+    while ( input_data > 1 ) {
+        input_data -= 1;
+        printf( "Hello World\n" );
+    }
+
+    // Inversed while loop (executes at least once)
+    do {
+        input_data -= 1;
+        printf( "Bye World\n" );
+        if ( input_data_copy == 0 )
+            goto this_is_a_label;
+    } while ( input_data_copy > 1 );
+
+this_is_a_label:
+    printf( "Jumped to label" );
+    return 0;
+}

semester3/spca/code-examples/00_c/00_basics/01_func.h

@@ -0,0 +1,4 @@
+#include <stdio.h> // Import from system path
+                   // (like library imports in other languages)
+
+int get_user_input_int( char prompt[] );

semester3/spca/code-examples/00_c/00_basics/02_declarations.c

@@ -0,0 +1,33 @@
+int my_int;              // Allocates memory on the stack.
+                         // Variable is global (read / writable by entire program)
+static int my_local_int; // only available locally (in this file)
+extern const char *var;  // Defined in some other file
+const int MY_CONST = 10; // constant (immutable), convention: SCREAM_CASE
+
+enum { ONE, TWO } num; // Enum. ONE will get value 0, TWO has value 1
+
+enum { O = 2, T = 1 } n; // Enum with values specified
+
+// Structs are like classes, but contain no logic
+struct MyStruct {
+        int el1;
+        int el2;
+};
+
+int fun( int j ) {
+    static int i = 0;              // Persists across calls of fun
+    short my_var = 1;              // Block scoped (deallocated when going out of scope)
+    int my_var_dbl = (int) my_var; // Explicit casting (works between almost all types)
+    return i;
+}
+
+int main( int argc, char *argv[] ) {
+    if ( ( my_local_int = fun( 10 ) ) ) {
+        // Every c statement is also an expression, i.e. you can do the above!
+    }
+    struct MyStruct test;            // Allocate memory on stack for struct
+    struct MyStruct *test_p = &test; // Pointer to memory where test resides
+    test.el1 = 1;                    // Direct element access
+    test_p->el2 = 2;                 // Via pointer
+    return 0;
+}

semester3/spca/code-examples/00_c/00_basics/03_arrays.c

@@ -0,0 +1,20 @@
+#include <stdint.h>
+#include <stdio.h>
+
+int main( int argc, char *argv[] ) {
+    int data[ 10 ];                  // Initialize array of 10 integers
+    data[ 5 ] = 5;                   // element 5 is now 5
+    *data = 10;                      // element 0 is now 5
+    printf( "%d\n", data[ 0 ] );     // print element 0 (prints 10)
+    printf( "%d\n", *data );         // equivalent as above
+    printf( "%d\n", data[ 5 ] );     // print element 5 (prints 5)
+    printf( "%d\n", *( data + 5 ) ); // equivalent as above
+    int multidim[ 5 ][ 5 ];          // 2-dimensional array
+                                     // We can iterate over it using two for-loops
+    int init_array[ 2 ][ 2 ] = {
+        {1, 2},
+        {3, 4}
+    };                       // We can initialize an array like this
+    int empty_arr[ 4 ] = {}; // Initialized to 0
+    return 0;
+}

semester3/spca/code-examples/00_c/00_basics/04_strings.c

@@ -0,0 +1,15 @@
+#include <stdio.h>
+#include <string.h>
+
+int main( int argc, char *argv[] ) {
+    char hello[ 6 ] = "hello";                           // Using double quotes
+    char world[ 6 ] = { 'w', 'o', 'r', 'l', 'd', '\0' }; // As array
+
+    char src[ 12 ], dest[ 12 ];
+    strncpy( src, "ETHZ", 12 );     // Copy strings (extra elements will be set to \0)
+    strncpy( dest, src, 12 );       // Copy strings (last arg is first n chars to copy)
+    if ( strncmp( src, dest, 12 ) ) // Compare two strings. Returns 1 if src > dest
+        printf( "Hello World" );
+    strncat( dest, " is in ZH", 12 ); // Concatenate strings
+    return 0;
+}