function pointer

.vscode/tasks.json

@@ -70,13 +70,22 @@
             "type": "cppbuild",
             "label": "C/C++: gcc.exe 활성 파일 빌드",
             "command": "C:/mingw64/bin/gcc.exe",
+            // main 다수 (테스트)
             "args": [
                 "-fdiagnostics-color=always",
                 "-g",
-                "${fileDirname}\\*.c",
+                "${file}",
                 "-o",
-                "${fileDirname}\\bin\\${fileBasenameNoExtension}.exe"
+                "${fileDirname}\\bin\\${fileBasenameNoExtension}.exe",
             ],
+            // // main 단일 프로젝트
+            // "args": [
+            //     "-fdiagnostics-color=always",
+            //     "-g",
+            //     "${fileDirname}\\*.c",
+            //     "-o",
+            //     "${fileDirname}\\bin\\${fileBasenameNoExtension}.exe"
+            // ],
             "options": {
                 "cwd": "C:/mingw64/bin"
             },

practice/lc_arrayAndPointers.c

@@ -0,0 +1,39 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+int main()
+{
+    char vowels[] = { 'A', 'E', 'I', 'O', 'U' };
+    char* pvowels = vowels;
+    
+    printf("Point the addresses\n");
+    for (int i = 0; i < 5; i++)
+    {
+        printf("&vowels[%d]: %p, pvowels + %d: %p, vowels + %d: %p\n", i, &vowels[i], i, pvowels + i, i, vowels + i);
+    }
+
+    printf("\nPoint the values\n");
+    for (int i = 0; i < 5; i++)
+    {
+        printf("vowels[%d]: %c, *(pvowels + %d): %c, *(vowels + %d): %c\n", i, vowels[i], i, *(pvowels + i), i, *(vowels + i));
+    }
+
+    // Dynamic malloc for array
+    int n = 4;
+    char* parr = (char*)malloc(n * sizeof(char));
+    parr[0] = 'L';
+    parr[1] = 'o';
+    parr[2] = 'V';
+    parr[3] = 'e';
+
+    for (int i = 0; i < n; i++)
+    {
+        printf("%c", parr[i]);
+    }
+
+    printf("\n");
+
+    free(parr);
+
+    return 0;
+}

practice/lc_functionArgsByReference.c

@@ -0,0 +1,51 @@
+#include <stdio.h>
+
+void addone(int n)
+{
+    n++;
+}
+
+void addoneByRef(int* n)
+{
+    (*n)++; 
+}
+
+typedef struct
+{
+    int x;
+    int y;
+} Point;
+
+void move1(Point* p)
+{
+    (*p).x++;
+    (*p).y++;
+}
+
+// 약어
+void move2(Point* p)
+{
+    p->x++;
+    p->y++;
+}
+
+int main()
+{
+    int n = 0;
+    printf("Step0: %d\n", n);
+    addone(n);
+    printf("Step2: %d\n", n);
+    addoneByRef(&n);
+    printf("Step2: %d\n", n);
+
+    printf("\n");
+
+    Point pt = { 1, 1 };
+    printf("Step0 pt.x: %d, pt.y: %d\n", pt.x, pt.y);
+    move1(&pt);
+    printf("Step1 pt.x: %d, pt.y: %d\n", pt.x, pt.y);
+    move2(&pt);
+    printf("Step2 pt.x: %d, pt.y: %d\n", pt.x, pt.y);
+
+    return 0;
+}

practice/lc_functionPointers.c

@@ -0,0 +1,37 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+void someFunction(int arg)
+{
+    printf("This is someFunction being called and arg is: %d\n", arg);
+    printf("Now, leaving the funciton!\n");
+}
+
+int compare(const void* left, const void* right)
+{
+    return (*(int*)right - *(int*)left);
+}
+
+int main()
+{
+    void (*pf)(int);
+    pf = &someFunction;
+    printf("We are about to call someFunction() using a pointer!\n");
+    (pf)(5);
+    printf("Wow that was cool!");
+
+    int (*cmp)(const void*, const void*);
+    cmp = &compare;
+
+    int iarray[] = {1,2,3,4,7,5,6,9,8};
+    qsort(iarray, sizeof(iarray) / sizeof(*iarray), sizeof(*iarray), cmp);
+
+    int c = 0;
+    while (c < sizeof(iarray) / sizeof(*iarray))
+    {
+        printf("%d\t", iarray[c]);
+        c++;
+    }
+
+    return 0;
+}

practice/lc_pointerArithmetics.c

@@ -0,0 +1,28 @@
+#include <stdio.h>
+
+int main()
+{
+    int intarray[5] = { 10, 20, 30, 40, 50 };
+
+    for (int i = 0; i < 5; i++)
+    {
+        printf("intarray[%d] has value %d - and address @ %x\n", i, intarray[i], &intarray[i]);
+    }
+
+    int* intpointer = &intarray[3];
+    printf("address %x - has value %d\n", intpointer, *intpointer);
+
+    intpointer++;
+    printf("address %x - has value %d\n", intpointer, *intpointer);
+
+    intpointer--;
+    printf("address %x - has value %d\n", intpointer, *intpointer);
+
+    intpointer -= 2;
+    printf("address %x - has value %d\n", intpointer, *intpointer);
+
+    intpointer += 2;
+    printf("address %x - has value %d\n", intpointer, *intpointer);
+
+    return 0;
+}

practice/lc_pointers.c

@@ -0,0 +1,14 @@
+#include <stdio.h>
+
+int main()
+{
+    int a = 1;
+    int * p = &a;
+
+    a += 1;
+    *p += 1;
+
+    printf("Value of a: %d\n", a);
+
+    return 0;
+}

practice/lc_recursion.c

@@ -0,0 +1,19 @@
+#include <stdio.h>
+
+unsigned int multiply(unsigned int x, unsigned int y)
+{
+    if (x == 1)
+        return y;
+    
+    if (x > 1)
+        return y + multiply(x - 1, y);
+
+    return 0;
+}
+
+int main()
+{
+    printf("3 times 100 is %d", multiply(3, 100));
+
+    return 0;
+}

practice/lc_structures.c

@@ -0,0 +1,30 @@
+#include <stdio.h>
+
+struct Point
+{
+    int x;
+    int y;
+};
+
+typedef struct
+{
+    char* brand; // 동적 할당을 위한 처리
+    int model;
+} Vehicle;
+
+int main()
+{
+    struct Point pt;
+    pt.x = 10;
+    pt.y = 5;
+
+    Vehicle vc;
+    vc.brand = "Ford";
+    vc.model = 2025;
+
+    printf("pt.x: %d\n", pt.x);
+    printf("pt.y: %d\n", pt.y);
+    printf("\n");
+    printf("vc.brand: %s\n", vc.brand);
+    printf("vc.model: %d\n", vc.model);
+}