{ "cells": [ { "cell_type": "markdown", "metadata": {}, "source": [ "# C++的数据类型" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "# 1. 数据类型" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## 1.1 整形" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "① 作用：整型变量表示的是整数类型的数据。\n", "\n", "② C++中能够表示整形的类型有以下几种方式，区别在于所占内存空间不同。\n", "\n", "③ 数据类型 占用空间 取值范围\n", "\n", "1. short(短整型) 2字节 -2^15-2^15-1\n", "2. int（整型） 4字节 -2^31-2^31-1\n", "3. long(长整型） Windows为4字节，Linux为4字节(32位)，8字节(64位) -2^31-2^31-1\n", "4. long long(长长整型) 8字节 -2^63-2^63-1" ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [ "#include \n", "using namespace std;\n", "\n", "int main()\n", "{\n", " //1、短整型(-32768~32767)\n", " short num1 = 10;\n", " short num5 = 32768; //溢出了，打印出来是-23768\n", " short num6 = 32770; //溢出了，打印出来是-32766\n", "\n", " //2、整型\n", " int num2 = 10;\n", "\n", " //3、长整型\n", " long num3 = 10;\n", "\n", " //4、长长整型\n", " long long num4 = 10;\n", "\n", " cout << \"num1 = ：\" << num1 << endl;\n", " cout << \"num2 = ：\" << num2 << endl;\n", " cout << \"num3 = ：\" << num3 << endl;\n", " cout << \"num4 = ：\" << num4 << endl;\n", " cout << \"num5 = ：\" << num5 << endl;\n", " cout << \"num6 = ：\" << num6 << endl;\n", "\n", " system(\"pause\");\n", "\n", " return 0;\n", "\n", "}" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "运行结果： \n", " - num1 = ：10 \n", " - num2 = ：10 \n", " - num3 = ：10 \n", " - num4 = ：10 \n", " - num5 = ：-32768 \n", " - num6 = ：-32766 \n", " - 请按任意键继续. . ." ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## 1.2 实型(浮点型)" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "① 作用：用于表示小数。\n", "\n", "② 浮点型变量分为下面两种，两个的区别在于表示有效数字范围不同。\n", "\n", "1. 单精度float\n", "2. 双精度double\n", "\n", "③ 数据类型 占用字节 有效数字范围\n", "\n", "1. float 4字节 7位有效数字\n", "2. double 8字节 15-16位有效数字" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "### 1.2.1 单精度、双精度" ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [ "#include \n", "using namespace std;\n", "\n", "int main()\n", "{\n", " //1、单精度 float\n", " //2、双精度 double\n", " //默认情况下，无论单精度还是双精度，都只会显示6位有效数字\n", " float f1 = 3.1415926; //默认为双精度，前面加float相当于把双精度转换为单精度\n", " float f2 = 3.1415926f; //后面加一个f，直接创建的是单精度\n", "\n", " cout << \"f1 = ：\" << f1 << endl;\n", "\n", " double d1 = 3.1415926;\n", "\n", " cout << \"d1 = ：\" << d1 << endl;\n", "\n", " cout << \"float 占用内存空间为\" << sizeof(float) << endl;\n", " cout << \"double 占用内层空间为\" << sizeof(double) << endl;\n", "\n", " system(\"pause\");\n", "\n", " return 0;\n", "\n", "}" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "运行结果： \n", " - f1 = ：3.14159 \n", " - d1 = ：3.14159 \n", " - float 占用内存空间为4 \n", " - double 占用内层空间为8 \n", " - 请按任意键继续. . ." ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "### 1.2.2 科学计数法" ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [ "#include \n", "using namespace std;\n", "\n", "int main()\n", "{\n", " //科学计数法\n", " float f3 = 3e2; // 3 * (10 ^ 2)\n", " cout << \"f3 = ：\" << f3 << endl;\n", "\n", " float f4 = 3e-2; // 3 * (0.1 ^ 2)\n", " cout << \"f4 = ：\" << f4 << endl;\n", "\n", " system(\"pause\");\n", "\n", " return 0;\n", "}" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "运行结果： \n", " - f3 = ：300 \n", " - f4 = ：0.03 \n", " - 请按任意键继续. . ." ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## 1.3 字符型" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "① 字符型变量用于显示单个字符。\n", "\n", "② 语法：char ch = 'a';\n", "\n", "③ 在显示字符型变量时，用单引号字符括起来，不要用双引号。\n", "\n", "④ 单引号内只能有一个字符，不可以是字符串。\n", "\n", "⑤ C和C++中字符型变量只占用1个字节。\n", "\n", "⑥ 字符型变量并不是把字符本身放到内存中存储，而是将对应的ASCII编码放入到存储单元。\n", "\n", "⑦ ASCII码大致由以下两部分组成：\n", "\n", "1. ASCII非打印控制字符：ASCII表上的数字0-31分配给了控制字符，用于控制像打印机等一些外围设备。\n", "2. ASCII打印字符：数字21-126分配给了能在键盘上找到的字符，当查看或打印文档时就会出现。" ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [ "#include \n", "using namespace std;\n", "\n", "int main()\n", "{\n", "\n", " //1、字符型变量创建方式\n", " char ch = 'a';\n", " cout << ch << endl;\n", "\n", " //2、字符型变量所占内存大小\n", " cout << \"char字符型变量所占内存：\" << sizeof(char) << endl;\n", "\n", " //3、字符型变量常见错误\n", " char ch2 = 'b'; //创建字符型变量时候，要用单引号\n", " //char ch3 = \"b\"; //错误，创建字符型变量时候，不能用双引号\n", " //char ch4 = 'abcdef'; //错误，创建字符型变量时候，单引号内只能有一个字符\n", "\n", " //4、字符型变量对应ASCII编码\n", " cout << (int)ch << endl; // (int)ch 为字符'a'的ASCIII码值\n", "\n", " system(\"pause\");\n", "\n", " return 0;\n", "\n", "}" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "运行结果： \n", " - a \n", " - char字符型变量所占内存：1 \n", " - 97 \n", " - 请按任意键继续. . ." ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## 1.4 字符串型" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "① 用于表示一串字符。\n", "\n", "② 字符串型有两种风格\n", "\n", "③ C风格字符串：char 变量名[] = \"字符串值\"\n", "\n", "④ C++风格字符串：string 变量名 = \"字符串值\"" ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [ "#include \n", "using namespace std;\n", "#include //用C++风格字符串时候，要包含这个头文件\n", "\n", "int main()\n", "{\n", "\n", " //1、C风格字符串\n", " //char 字符 = 这是一个字符\n", " //char 字符[] = 这是一个字符串\n", " //表示字符串时，等号后面，要用双引号\n", "\n", " char str[] = \"hello world\";\n", " cout << str << endl;\n", "\n", " //2、C++风格字符串\n", " string str2 = \"hello world\";\n", " cout << str2 << endl;\n", " \n", " system(\"pause\");\n", "\n", " return 0;\n", "\n", "}" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "运行结果： \n", " - hello world \n", " - hello world \n", " - 请按任意键继续. . ." ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## 1.5 布尔类型 bool" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "① 布尔数据类型代表真或假的值。\n", "\n", "② bool类型只有两个值：\n", "\n", "1. true -- 真 (本质是1)\n", "2. false -- 假(本质是0)\n", "\n", "③ bool类型占1个字节大小" ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [ "#include \n", "using namespace std;\n", "\n", "int main()\n", "{\n", "\n", " //1、创建bool数据类型\n", "\n", " bool flag1 = true; //true代表真\n", " cout << flag1 << endl;\n", " \n", " bool flag2 = false; //flag 代表假\n", " cout << flag2 << endl;\n", " \n", " //本质上 1代表真 0代表假\n", "\n", " //2、查看bool类型所占空间\n", " cout << \"bool所占内存空间：\" << sizeof(flag1) << endl;\n", " cout << \"bool所占内存空间：\" << sizeof(flag2) << endl;\n", "\n", " system(\"pause\");\n", "\n", " return 0;\n", "\n", "}" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "运行结果： \n", " - 1 \n", " - 0 \n", " - bool所占内存空间：1 \n", " - bool所占内存空间：1 \n", " - 请按任意键继续. . ." ] } ], "metadata": { "kernelspec": { "display_name": "Python 3.6.3", "language": "python", "name": "python3.6.3" }, "language_info": { "codemirror_mode": { "name": "ipython", "version": 3 }, "file_extension": ".py", "mimetype": "text/x-python", "name": "python", "nbconvert_exporter": "python", "pygments_lexer": "ipython3", "version": "3.6.3" }, "toc": { "base_numbering": 1, "nav_menu": {}, "number_sections": false, "sideBar": true, "skip_h1_title": false, "title_cell": "Table of Contents", "title_sidebar": "Contents", "toc_cell": false, "toc_position": {}, "toc_section_display": true, "toc_window_display": true } }, "nbformat": 4, "nbformat_minor": 4 }