入門C++編程，從零開始學習基礎語法和實現程序

C++是一種高級編程語言，被廣泛應用於開發操作系統、瀏覽器、遊戲等軟件，是計算機專業學生必修的一門課程。本文將介紹從零開始學習C++編程的基礎語法和實現程序的一些知識和技巧。

一、數據類型

C++中的基本數據類型包括整型、浮點型、字符型和布爾型，其中整型包括short、int和long三個類型，浮點型包括float和double兩個類型，字符型是用來表示單個字符，布爾型只有兩個值：true和false。

#include <iostream>
using namespace std;

int main()
{
    int num = 10;
    float f = 3.14;
    char ch = 'a';
    bool flag = true;

    cout << "num = " << num << endl;
    cout << "f = " << f << endl;
    cout << "ch = " << ch << endl;
    cout << "flag = " << flag << endl;

    return 0;
}

輸出結果：

num = 10
f = 3.14
ch = a
flag = 1

可以看到，布爾型的true被輸出為1，false被輸出為0。

二、運算符

C++中的運算符包括算術運算符、關係運算符、邏輯運算符、位運算符和賦值運算符。

算術運算符包括加、減、乘、除和取模運算，關係運算符包括等於、不等於、大於、小於、大於等於和小於等於運算，邏輯運算符包括與、或和非運算，位運算符包括按位與、按位或、按位取反和按位異或運算，賦值運算符包括等於、加等於、減等於、乘等於、除等於和取模等於運算。

#include <iostream>
using namespace std;

int main()
{
    int a = 10, b = 20;
    cout << "a + b = " << a + b << endl;
    cout << "a - b = " << a - b << endl;
    cout << "a * b = " << a * b << endl;
    cout << "a / b = " << a / b << endl;
    cout << "a % b = " << a % b << endl;

    int c = 30, d = 30;
    cout << "c == d: " << (c == d) << endl;
    cout << "c != d: " << (c != d) << endl;
    cout < d: " < d) << endl;
    cout << "c < d: " << (c < d) << endl;
    cout <= d: " <= d) << endl;
    cout << "c <= d: " << (c <= d) << endl;

    bool e = true, f = false;
    cout << "e && f: " << (e && f) << endl;
    cout << "e || f: " << (e || f) << endl;
    cout << "!e: " << !e << endl;

    int g = 0x5, h = 0x3;
    cout << "g & h: " << (g & h) << endl;
    cout << "g | h: " << (g | h) << endl;
    cout << "~g: " << ~g << endl;
    cout << "g ^ h: " << (g ^ h) << endl;

    int i = 5, j = 10;
    i += j;
    cout << "i += j: " << i << endl;
    i -= j;
    cout << "i -= j: " << i << endl;
    i *= j;
    cout << "i *= j: " << i << endl;
    i /= j;
    cout << "i /= j: " << i << endl;
    i %= j;
    cout << "i %= j: " << i << endl;

    return 0;
}

輸出結果：

a + b = 30
a - b = -10
a * b = 200
a / b = 0
a % b = 10
c == d: 1
c != d: 0
c > d: 0
c = d: 1
c <= d: 1
e && f: 0
e || f: 1
!e: 0
g & h: 1
g | h: 7
~g: -6
g ^ h: 6
i += j: 15
i -= j: 5
i *= j: 50
i /= j: 5
i %= j: 5

三、控制語句

C++中的控制語句包括順序結構、選擇結構和循環結構。

順序結構是指按照代碼的先後順序依次執行每一條語句，例如：

#include <iostream>
using namespace std;

int main()
{
    int x = 10, y = 20, z = 30;
    cout << "x = " << x << endl;
    cout << "y = " << y << endl;
    cout << "z = " << z << endl;

    return 0;
}

輸出結果：

x = 10
y = 20
z = 30

選擇結構是指根據條件的真假來判斷執行哪一條語句，包括if語句和switch語句。

#include <iostream>
using namespace std;

int main()
{
    int x = 10;
    if (x < 0) {
        cout << "x is negative" << endl;
    } else if (x == 0) {
        cout << "x is zero" << endl;
    } else {
        cout << "x is positive" << endl;
    }

    int y = 2;
    switch (y) {
        case 1:
            cout << "y is one" << endl;
            break;
        case 2:
            cout << "y is two" << endl;
            break;
        default:
            cout << "y is not one or two" << endl;
            break;
    }

    return 0;
}

輸出結果：

x is positive
y is two

循環結構是指重複執行一段代碼，包括while循環、do-while循環和for循環。

#include <iostream>
using namespace std;

int main()
{
    int x = 0;
    while (x < 5) {
        cout << "x = " << x << endl;
        x++;
    }

    int y = 0;
    do {
        cout << "y = " << y << endl;
        y++;
    } while (y < 5);

    for (int i = 0; i < 5; i++) {
        cout << "i = " << i << endl;
    }

    return 0;
}

輸出結果：

x = 0
x = 1
x = 2
x = 3
x = 4
y = 0
y = 1
y = 2
y = 3
y = 4
i = 0
i = 1
i = 2
i = 3
i = 4

四、函數

函數是一段可以重複使用的代碼，可以實現特定的功能。在C++中定義一個函數需要指定函數的返回類型、函數名稱和參數列表，例如：

#include <iostream>
using namespace std;

int add(int a, int b) {
    return a + b;
}

int main()
{
    int x = 2, y = 3;
    cout << "x + y = " << add(x, y) << endl;

    return 0;
}

輸出結果：

x + y = 5

五、數組

數組是一種存儲一組數據的結構，C++支持靜態數組和動態數組。靜態數組在定義時需要指定數組的長度，動態數組可以在運行時進行分配和釋放。

#include <iostream>
using namespace std;

int main()
{
    int arr1[5] = {1, 2, 3, 4, 5};
    for (int i = 0; i < 5; i++) {
        cout << "arr1[" << i << "] = " << arr1[i] << endl;
    }

    int arr2[] = {1, 2, 3, 4, 5};
    for (int i = 0; i < 5; i++) {
        cout << "arr2[" << i << "] = " << arr2[i] << endl;
    }

    int* arr3 = new int[5];
    for (int i = 0; i < 5; i++) {
        arr3[i] = i + 1;
        cout << "arr3[" << i << "] = " << arr3[i] << endl;
    }
    delete[] arr3;

    return 0;
}

輸出結果：

arr1[0] = 1
arr1[1] = 2
arr1[2] = 3
arr1[3] = 4
arr1[4] = 5
arr2[0] = 1
arr2[1] = 2
arr2[2] = 3
arr2[3] = 4
arr2[4] = 5
arr3[0] = 1
arr3[1] = 2
arr3[2] = 3
arr3[3] = 4
arr3[4] = 5

六、指針

指針是C++中的重要概念，可以通過指針來訪問內存中的數據。指針變量存儲的是內存地址。

#include <iostream>
using namespace std;

int main()
{
    int num = 10;
    int* p = &num;
    cout << "num = " << num << endl;
    cout << "p = " << p << endl; // 輸出的是指針變量p所指向的內存地址
    cout << "*p = " << *p << endl; // 輸出的是p所指向的內存地址中的值

    int arr[5] = {1, 2, 3, 4, 5};
    int* q = arr; // 數組名本身就是一個指針
    for (int i = 0; i < 5; i++) {
        cout << "arr[" << i << "] = " << *(q + i) << endl;
    }

    return 0;
}

輸出結果：

num = 10
p = 0x7ffee7b46bdc
*p = 10
arr[0] = 1
arr[1] = 2
arr[2] = 3
arr[3] = 4
arr[4] = 5

七、文件操作

C++中的文件操作包括文件的讀寫和文件指針的操作。文件指針指向文件中的某個位置，可以通過文件指針進行讀寫。

#include <iostream>

#include <fstream>

using namespace std;
int main()
{
 ofstream fout("data.txt"); // 打開文件用於寫入
 for (int i = 1; i <= 5; i++) {
 fout << i <> num) { // 從文件中讀取數據
 cout << num << endl;
 }
 fin
原創文章，作者：小藍，如若轉載，請註明出處：https://www.506064.com/zh-hk/n/187221.html