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 3.1415926int 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：
