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Original Course link: Interacting with the System and Managing Memory Module 2: Dynamic allocation most of the memory we have used has been located on the stack. Dynamic memory allocation gives a programmer much more flexibility, in that it allows you to request a specific amount memory to be allocated on the heap, so that it will not disappear with the stack frame of the calling function. heap vs. stack Stack vs Heap: What’s the difference? (educative.io) ...

shell shebang line (#!/bin/bash to tell the system which interpreter to use special or wired file name delimeter \ tab, to show the special or wired file name such as : % touch "23\\?\$*'MaRViN'*$?77&\\" -rw-r--r-- 1 linxu 2024_heilbronn 0 Jan 17 21:20 \?$*'MaRViN'*0\ % rm \\\?\$\*\'MaRViN\'\*0\\ # input \ and then click tab, the terminal will show us \\?\$\*\'MaRViN\'\*0\\ automatically, # for us to confirm it automatically. % ls -lRa *MaRV* | cat -e -rw-r--r-- 1 linxu 2024_heilbronn 3 Jan 17 21:51 "\?$*MaRViN*$?\"$ # the file size 3, it is wrong, use echo and terminator % to end the input % echo -n 42 > \"\\\?\$\*MaRViN\*\$\?\\\" % cat \"\\\?\$\*MaRViN\*\$\?\\\" 42% # The function of the % mark is to indicate that the prompt is on the same line as the output, # because there is no linefeed character at the end of the output. This can help you distinguish # between the output and the prompt, and avoid confusion. However, some shells may use different # symbols or colors to indicate this situation. man how to modify the file size, time, dates, link number, in terminal unix. how to use and read command manual. ...

Week 3, Multidimensional Arrays Incompatible Representations C语言中多维数组中不兼容表示 参考更多案例： github/c3w3_1.segmentation_fault.c github/c3w3_1.compiler_wrong.c #include <stdio.h> void printArray(int (*arr)[5], int rows) { for (int i = 0; i < rows; ++i) { for (int j = 0; j < 5; ++j) { printf("%d ", arr[i][j]); } printf("\n"); } } int main() { int twoDArray[3][5] = { {1, 2, 3, 4, 5}, {6, 7, 8, 9, 10}, {11, 12, 13, 14, 15} }; // 这将有效，因为函数期望一个指向包含5个整数的数组的指针 printArray(twoDArray, 3); return 0; }

Week 2, Read pointer 2 #include <stdio.h> #include <stdlib.h> int f(int **r, **s){ int temp = **r; int temp2 = **s; int *z = *r; *r = *s; *s = z; printf("**r = %d\n",**r); printf("**s = %d\n",**s); *z += 3; **s -= 8; **r -= 19; return temp + temp2; } int main(void) { int a = 80; int b = 12; int * p = &a; int * q = &b; int x = f(&p, &q); printf("x = %d\n", x); printf("*p = %d\n", *p); printf("*q = %d\n", *q); printf("a = %d\n", a); printf("b = %d\n", b); return EXIT_SUCCESS; } Output **r = 12 **s = 80 x = 92 *p = -7 *q = 75 a = 75 b = -7 ...

Original Course link: Pointers, Arrays, and Recursion Week 1, Read pointer 1 C pointer C语言指针详解，30分钟玩转C语言指针 (biancheng.net) C语言指针变量的定义和使用（精华）_54笨鸟 (54benniao.com) #include <stdio.h> #include <stdlib.h> void g(int x, int * y) { printf("In g, x = %d, *y = %d\n", x, *y); x++; *y = *y - x; y = &x; } void f(int * a, int b) { printf("In f, *a = %d, b = %d\n", *a, b); *a += b; b *= 2; // * multiply, not pointer identifier here; g(*a, &b); printf("Back in f, *a = %d, b = %d\n", *a, b); } int main(void) { int x = 3; int y = 4; f(&x, y); printf("In main: x = %d, y = %d\n", x, y); return EXIT_SUCCESS; } Output In f, *a = 3, b = 4 In g, x = 7, *y = 8 Back in f, *a = 7, b = 0 In main: x = 7, y = 4 ...