C语言概述
- 打印摄氏度
/* 1.1 使用int类型进行计算 */
#include <stdio.h>
/* print Fahrenheit-Celsius table
for fahr = 0, 20, ...., 300 */
main()
{
int fahr, celsius;
int lower, upper, step;
lower = 0; /* lower limit of temperature table */
upper = 300; /* upper limit */
step = 20; /* step size */
fahr = lower;
while(fahr <= upper) {
celsius = 5 * (fahr - 32) / 9;
printf("%d\t%d\n", fahr, celsius);
// printf(""%3d %6d\n", fahr, celsius); /* right-justified */
fahr = fahr + step;
}
}
/* 1.2 使用 float 类型进行计算 */
#include <stdio.h>
main()
{
float fahr, celsius;
int lower, upper, step;
lower = 0;
upper = 300;
step = 20;
fahr = lower;
while(fahr <= upper) {
celsius = (5.0 / 9.0) * (fahr - 32.0);
// fahr 3个字符宽度,无小数部分; celsius 6个字符宽度,额外包括一个小数位
printf("%3.0f %6.1f\n", fahr, celsius);
fahr = fahr + step;
}
}
/* 1.3 使用for循环语句 */
#include <stdio.h>
main()
{
int fahr;
for(fahr = 0; fahr <= 300; fahr = fahr + 20) {
printf("%3d %6.1f\n", fahr, (5.0 / 9.0)*(fahr - 32));
}
}
/* 1.4 符号常量的应用
因为单纯的数字(如300,20),表达的意义非常模糊,不易于阅读 */
#include <stdio.h>
// 定义符号常量
#define LOWER 0
#define UPPER 300
#define STEP 20
main()
{
int fahr;
for(fahr = LOWER; fahr <= UPPER; fahr = fahr + STEP) {
printf("%3d %6.1f\n", fahr, (5.0 / 9.0) * (fahr - 32));
}
}
- 数据类型:
-
基本数据类型:
- int
- short
- long
- float
- double
- char
- arrays
- structures
- unions
- pointers
-
printf()说明:%d: 十进制整数(decimal)%f: floating point%o: octal(八进制)%x: hexadecimal(十六进制)%c: character%s: string%%: %
-
- 字符串的处理
/* file copying (version 1) */
#include <stdio.h>
main()
{
int c;
while((c = getchar()) != EOF)
putchar(c);
}
/* character counting */
#include <stdio.h>
main()
{
long nc;
for(nc = 0; getchar() != EOF; ++nc)
;
printf("%.0f\n", nc);
}
/* line counting */
#include <stdio.h>
main()
{
int c, nl;
nl = 0;
while((c = getchar()) != EOF)
if (c == '\n')
++nl;
printf("%d\n", nl);
}
/* 1-9:
Write a program to copy its input to its output, replacing each string of one or more
blanks by a single blank */
/* version 1*/
#include <stdio.h>
#define NONBLANK '-'
int main(void)
{
int c, lastc;
lastc = NONBLANK;
while((c = getchar()) != EOF) {
if(c == ' ') {
if(lastc != ' ') {
putchar(c);
}
} else {
putchar(c);
}
lastc = c;
}
return 0;
}
/* a bare-bones version of the UNIX program wc */
#include <stdio.h>
#define IN 1
#define OUT 0
main()
{
int c, nl, nw, nc, state;
state = OUT;
nl = nw = nc = 0;
while((c = getchar()) != EOF) {
++nc;
if (c == '\n') {
++nl;
}
if (c == ' ' || c == '\n' || c == '\t') {
state = OUT;
} else if (state == OUT) {
state = IN;
++nw;
}
}
printf("%d %d %d\n", nl, nw, nc);
}
