1、符号常量
#define 符号常量名 常量
使用符号常量计算圆柱体的体积：
#include <stdio.h> #define PI 3.1415926 int main() { float r, h, volum; printf("Please enter the radius: "); scanf("%f", &r); printf("Please enter the height of the cylinder: "); scanf("%f", &h); volum = PI * r * r * h; printf("The volume of a cylinder is %f\n", volum); return 0; }
- 运行结果：
2、变量的赋值和初始化
输入两个数据，交换他们的值：
#include <stdio.h> int main() { int a, b, t; a = 5; b = 8; printf("a = %d, b = %d\n", a, b); printf("Exchange two data: \n"); t = a; a = b; b = t; printf("a = %d, b = %d\n", a, b); return 0; }
- 运行结果：
3、有符号数和无符号数
输入两个无符号数据，比较他们的大小：
#include <stdio.h> int main() { unsigned int data1, data2; printf("Please enter two numbers: "); scanf(" %d %d ", &data1, &data2); if (data1 > data2) { printf("The first number is larger than the second"); } else { printf("The first number is smaller than the second"); } return 0; }
- 运行结果：
4、字符型数据
大写转小写：
#include <stdio.h> int main() { char c; printf("Please enter character: "); c = getchar(); if (c >= 'A' && c <= 'Z') { c += 32; } printf("Output: \n"); printf("%c\t%d", c, c); return 0; }
- 运行结果：
5、隐式转换
输入半径，计算圆的面积：
#include <stdio.h> int main() { float pi = 3.1416; int r, area; printf("Please enter radius: "); scanf("%d", &r); area = pi * r * r; printf("Area is: %d", area); return 0; }
- 运行结果：
6、显示转换
输入学生的 3 门课程的成绩，求其平均成绩：
#include <stdio.h> int main() { int mathscore, average_int; float chinscore, engscore, average_implicit, average_explicit_int; printf("Please enter the results of math, Chinese and English: \n"); scanf("%d %f %f", &mathscore, &chinscore, &engscore); average_implicit = (mathscore + chinscore + engscore) / 3; average_explicit_int = (mathscore + (int)(chinscore) + (int)(engscore)) / 3; average_int = (int)((mathscore + (int)(chinscore) + (int)(engscore)) / 3); printf("%.1f %.1f %d", average_implicit, average_explicit_int, average_int); return 0; }
- 运行结果：
7、算术表达式
从键盘上输入一个三位的整数，分别输出个位、十位、百位上的数字
#include <stdio.h> int main() { int num; int ones, tens, hundreds; printf("Please enter a number: "); scanf("%d", &num); hundreds = num / 100; tens = (num - hundreds * 100) / 10; ones = num % 10; printf("The ones place is %d, the tens place is %d, and the hundreds place is %d", ones, tens, hundreds); return 0; }
- 运行结果：
8、关系表达式
输出关系表达式：
#include <stdio.h> int main() { int score = 95, a, b, c; a = 70; b = 'a' == 'a'; c = 'a' != 'A'; printf("a = %d, b = %d, c = %d\n", a, b, c); return 0; }
- 运算结果：
9、逻辑表达式
输入一个年份，判断其是否是闰年：
#include <stdio.h> int main() { int year; printf("Please enter the year: "); scanf("%d", &year); if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0) { printf("%d is leao year\n", year); } else { printf("%d is not leap year\n", year); } return 0; }
- 运算结果：
10、赋值表达式
复合赋值运算符在程序中的简单使用：
#include <stdio.h> void main() { int a = 3, b = 8; a += a -= a * a; b %= 4 - 1; b += b *= b -= b *= 3; printf("a = %d, b = %d", a, b); }
- 运算结果：
11、自增、自减运算符
前置加和后置加大的区别：
#include <stdio.h> int main() { int a, b, c; a = 7; printf("a = %d\n", a); b = ++a; printf("(1) ++a = %d a = %d\n", b, a); a = 7; c = a++; printf("(2) a++ = %d a = %d\n", c, a); return 0; }
- 运算结果：
12、逗号运算符
逗号表达式的应用：
#include <stdio.h> void main() { int a, b, c, d; a = b = 1; d = (c = a++, ++b, b++); printf("a = %d, b = %d, c = %d, d = %d", a, b, c, d); }
- 运算结果：
13、条件运算符
求最大值：
#include <stdio.h> void main() { int a, b, max; printf("Please enter two numbers: "); scanf("%d %d", &a, &b); max = a > b ? a : b; printf("The maximum value of both %d and %d is: %d", a, b, max); }
- 运算结果：
14、位运算赋值运算符
取一个整数的二进制形式从右端开始的若干位，并以八进制形式输出：
#include <stdio.h> int main() { unsigned short a, b, c, d; int i, k; printf("Please enter this integer: "); scanf("%o", &a); printf("Please enter the start position of the intercept bit (the low position starts from 0) and the end position (the high position): \n"); scanf("%d %d", &i, &k); b = a >> (k - i + 1); c = ~(~0 << (k - i + 1)); d = b & c; printf("The integer %o truncated from %d to %d bits is %o\n", a, i, k, d); return 0; }
- 运算结果
15、四则运算计算器
输入两个整数，计算它的和、差、积、商、余数：
#include <stdio.h> int main() { int num1, num2, i = 1, add, sub, mul, div, rem, flag; printf("Please enter the first and second numbers: "); scanf("%d %d", &num1, &num2); add = num1 + num2; sub = num1 - num2; mul = num1 * num2; if (num2 != 0) { flag = 1; div = (float)num1 / (float)num2; rem = num1 % num2; } else { flag = 0; } printf("%d.Sum is %d\n", i++, add); printf("%d.Difference is %d\n", i++, sub); printf("%d.Product is %d\n", i++, mul); (flag == 0) ? printf("%d.The input divisor is 0, and the quotient cannot be calculated\n", i++) : printf("%d.Quotient is %d\n", i++, div); (flag == 0) ? printf("%d.The input divisor is 0, and the remainder cannot be calculated\n", i++) : printf("%d.Remainder is %d\n", i++, rem); return 0; }
- 运算结果：
