C 實際示例

// 學生資料
int studentID = 15;
int studentAge = 23;
float studentFee = 75.25;
char studentGrade = 'B';

// 列印變數
printf("Student id: %d\n", studentID);
printf("Student age: %d\n", studentAge);
printf("Student fee: %f\n", studentFee);
printf("Student grade: %c", studentGrade);

// 建立整數變數
int length = 4;
int width = 6;
int area;

// 計算矩形的面積
area = length * width;

// 列印變數
printf("Length is: %d\n", length);
printf("Width is: %d\n", width);
printf("Area of the rectangle is: %d", area);

// 建立不同資料型別的變數
int items = 50;
float cost_per_item = 9.99;
float total_cost = items * cost_per_item;
char currency = '$';

// 列印變數
printf("Number of items: %d\n", items);
printf("Cost per item: %.2f %c\n", cost_per_item, currency);
printf("Total cost = %.2f %c\n", total_cost, currency);

// 將遊戲中可能獲得的最大分數設定為 500
int maxScore = 500;

// 使用者的實際分數
int userScore = 423;

// 計算使用者分數佔最大可用分數的百分比
float percentage = (float) userScore / maxScore * 100.0;

// 列印百分比
printf("User's percentage is %.2f", percentage);

int myAge = 25;
int votingAge = 18;

printf("%d", myAge >= votingAge); // 返回 1 (true)，表示 25 歲的人可以投票！

int myAge = 25;
int votingAge = 18;

if (myAge >= votingAge) {
  printf("Old enough to vote!");
} else {
  printf("Not old enough to vote.");
}

int time = 20;
if (time < 18) {
  printf("Good day.");
} else {
  printf("Good evening.");
}

int doorCode = 1337;

if (doorCode == 1337) {
  printf("Correct code.\nThe door is now open.");
} else {
  printf("Wrong code.\nThe door remains closed.");
}

int myNum = 10;

if (myNum > 0) {
  printf("The value is a positive number.");
} else if (myNum < 0) {
  printf("The value is a negative number.");
} else {
  printf("The value is 0.");
}

int myAge = 25;
int votingAge = 18;

if (myAge >= votingAge) {
  printf("Old enough to vote!");
} else {
  printf("Not old enough to vote.");
}

int myNum = 5;

if (myNum % 2 == 0) {
  printf("%d is even.\n", myNum);
} else {
  printf("%d is odd.\n", myNum);
}

int day = 4;

switch (day) {
  case 1
    printf("Monday");
    break;
  case 2
    printf("Tuesday");
    break;
  case 3
    printf("Wednesday");
    break;
  case 4
    printf("Thursday");
    break;
  case 5
    printf("Friday");
    break;
  case 6
    printf("Saturday");
    break;
  case 7
    printf("Sunday");
    break;
}

int countdown = 3;

while (countdown > 0) {
  printf("%d\n", countdown);
  countdown--;
}

printf("Happy New Year!!\n");

int dice = 1;

while (dice <= 6) {
  if (dice < 6) {
    printf("No Yatzy\n");
  } else {
    printf("Yatzy!\n");
  }
  dice = dice + 1;
}

// 一個包含一些特定數字的變數
int numbers = 12345;

// 一個儲存反轉後數字的變數
int revNumbers = 0;

// 反轉並重新排序數字
while (numbers) {
  // 獲取 'numbers' 的最後一個數字並將其新增到 'revNumber'
  revNumbers = revNumbers * 10 + numbers % 10;
  // 從 'numbers' 中移除最後一個數字
  numbers /= 10;
}

int i;

for (i = 0; i <= 10; i = i + 2) {
  printf("%d\n", i);
}

for (i = 0; i <= 100; i += 10) {
  printf("%d\n", i);
}

for (i = 2; i <= 512; i *= 2) {
  printf("%d\n", i);
}

int number = 2;
int i;

// 列印數字 2 的乘法表
for (i = 1; i <= 10; i++) {
  printf("%d x %d = %d\n", number, i, number * i);
}

return 0;

// 一個儲存不同年齡的陣列
int ages[] = {20, 22, 18, 35, 48, 26, 87, 70};

float avg, sum = 0;
int i;

// 獲取陣列的長度
int length = sizeof(ages) / sizeof(ages[0]);

// 遍歷陣列元素
for (int i = 0; i < length; i++) {
  sum += ages[i];
}

// 透過將總和除以長度來計算平均值
avg = sum / length;

// 列印平均值
printf("The average age is: %.2f", avg);

// 一個儲存不同年齡的陣列
int ages[] = {20, 22, 18, 35, 48, 26, 87, 70};

// 獲取陣列的長度
int length = sizeof(ages) / sizeof(ages[0]);

// 建立一個變數並將 ages 的第一個陣列元素賦給它
int lowestAge = ages[0];

// 遍歷 ages 陣列的元素以查詢最小年齡
for (int i = 0; i < length; i++) {
  if (lowestAge > ages[i]) {
    lowestAge = ages[i];
  }
}

char message[] = "Good to see you,";
char fname[] = "John";

printf("%s %s!", message, fname);

char word[] = "Computer";
printf("The word '%s' has %d characters in it.", word, strlen(word));

char fullName[30];

printf("Type your full name: \n");
fgets(fullName, sizeof(fullName), stdin);

printf("Hello %s", fullName);

// 將華氏度轉換為攝氏度的函式
float toCelsius(float fahrenheit) {
  return (5.0 / 9.0) * (fahrenheit - 32.0);
}

int main() {
  // 設定一個華氏度值
  float f_value = 98.8;

  // 使用華氏度值呼叫函式
  float result = toCelsius(f_value);

  // 列印華氏度值
  printf("Fahrenheit: %.2f\n", f_value);

  // 列印結果
  printf("Convert Fahrenheit to Celsius: %.2f\n", result);

  return 0;
}

struct Car {
  char brand[50];
  char model[50];
  int year;
};

int main() {
  struct Car car1 = {"BMW", "X5", 1999};
  struct Car car2 = {"Ford", "Mustang", 1969};
  struct Car car3 = {"Toyota", "Corolla", 2011};

  printf("%s %s %d\n", car1.brand, car1.model, car1.year);
  printf("%s %s %d\n", car2.brand, car2.model, car2.year);
  printf("%s %s %d\n", car3.brand, car3.model, car3.year);

  return 0;
}

struct list {
  int *data; // 指向儲存列表項的記憶體
  int numItems; // 指示列表中當前有多少項
  int size; // 指示已分配記憶體中可以容納多少項
};

void addToList(struct list *myList, int item);

int main() {
  struct list myList;
  int amount;

  // 建立一個列表，併為 10 個專案分配空間
  myList.numItems = 0;
  myList.size = 10;
  myList.data = malloc(myList.size * sizeof(int));

  // 查詢記憶體分配是否成功
  if (myList.data == NULL) {
    printf("Memory allocation failed");
    return 1; // 以錯誤程式碼退出程式
  }

  // 將指定數量的專案新增到列表中
  amount = 44;
  for (int i = 0; i < amount; i++) {
    addToList(&myList, i + 1);
  }

  // 顯示列表內容
  for (int j = 0; j < myList.numItems; j++) {
    printf("%d ", myList.data[j]);
  }

  // 在不再需要時釋放記憶體
  free(myList.data);
  myList.data = NULL;

  return 0;
}

// 此函式向列表中新增一個專案
void addToList(struct list *myList, int item) {

  // 如果列表已滿，則將記憶體大小調整為可容納另外 10 個專案
  if (myList->numItems == myList->size) {
    myList->size += 10;
    myList->data = realloc( myList->data, myList->size * sizeof(int) );
  }

  // 將專案新增到列表末尾
  myList->data[myList->numItems] = item;
  myList->numItems++;
}