第7章 c控制语句分支和跳转
求出温度第一零度的天数的百分率
#include <stdio.h>
void main()
{
const int FREEZING = 0;
float temprature ;
int cold_dat = 0;
int all_days= 0;
printf("Enter the list of daily low temperature \n");
printf("Use celsius and enter q to quit .\n");
while (scanf ("%f",&temprature) == 1)
{
all_days++;
if (temprature < FREEZING) {
cold_dat ++;
}
}
if (all_days != 0) {
printf("%d day total : %1.f ％％ were below freezing .\n",all_days,100.0* (float)cold_dat/all_days);
}
if (all_days == 0) {
printf("%d no data entered" );
}
}
if只要不为0 就打开。
#include <stdio.h>
void main()
{
if (-1) {
printf("hello = -1");
}
if (0) {
printf("hello =0");
}
if (-1) {
printf("hello = -1");
}
printf("hello = 0");
}
改变输入，只保留其中的空格
#include <stdio.h>
#define SPACE ' '
void main()
{
char ch ;
ch =getchar();
while (ch != '\n') {
if (ch == SPACE) {
putchar(ch);
}
else {
putchar(ch +1);
}
ch =getchar();
}
}
#include <stdio.h>
#define SPACE ' '
void main()
{
char ch ;
while ( (ch = getchar() )!= '\n') {
if (ch == SPACE) {
putchar(ch);
}
else {
putchar(ch +1);
}
}
}
改变输入，只保留非字母字符
#include <stdio.h>
#include <ctype.h>
void main()
{
char ch;
while ((ch = getchar()) != '\n') {
if (isalpha(ch)) {
putchar(ch +1);
}
else
{
putchar(ch);
}
}
putchar(ch);//打印换行字符
}
j计算用电账目
#include <stdio.h>
#define RATE1 0.12589
#define RATE2 0.17901
#define RATE3 0.20971
#define BRESK1 360.0
#define BRESK2 680.0
#define BASE1 (RATE1*BRESK1)
#define BASE2 ( BASE1 + (RATE2 * ( BRESK2 - BRESK2)))
void main()
{
double kwh;
double bill;
printf("please enter the kwh used .\n" );
scanf("%lf",&kwh);
if (kwh <= BRESK1) {
bill =RATE1 * kwh;
}
else if (kwh <= BRESK2)
{
bill =BASE1 + (RATE2 * (kwh - BRESK1));
}
else bill = BASE2 + ( RATE3 * (kwh - BRESK2) );
printf("the chare for %.1f kwh is $ %.2f .\n",kwh , bill);
}
使用嵌套if 现实一个数的约数
#include <stdio.h>
#include <stdbool.h>
main()
{
unsigned longnum , div;
bool isPrme;
printf("Please enter an integer for analysis ");
printf("enter q to qutie .\n");
while (scanf("%lu",&num ) ==1 ) {
for (div = 2 , isPrme = true ; (div * div) <= num ; div++)
{
if (num %div ==0) {
if ((div *div) != num)
{
printf("%lu is divisidle by %lu and %lu .\n",num,div ,num/div );
}
else printf("%lu is divisivle %lu .\n ", num ,div);
}
isPrme =false;
}
if (isPrme) {
printf("%lu is prime .\n",num);
}
printf("Please enter an integer for analysis ");
printf("enter q to qutie .\n");
}
printf("bey.\n");
}
#include
#define PERIOD '.'
void main()
{
int ch , charcount = 0 ;
while ((ch = getchar()) != PERIOD ) {
if (ch != '"' && ch != '\'')
charcount ++ ;
}
printf("There are %d non-quote character .\n",charcount);
}
统计字符 单词和行
#include <stdio.h>
#include <ctype.h>
#include <stdbool.h>
#define STOP '|'
void main()
{
char c , prev ;
long n_chas = 0L;
intn_lines =0;
int n_words = 0;
int n_plines = 0;
bool inword = false;
printf ("Enter text to be analyzed \n") ;
prev ='\n';
while ((c = getchar() != STOP)) {
n_chas ++;
if (c == '\n') {
n_lines ++;
}
if ( !isspace(c) && !inword)
{
inword =true;
n_words ++;
}
if( isspace(c) && inword)
{
inword =false;
}
prev = c;
}
if (prev != '\n') {
n_lines =1;
}
printf("character = %ld , words = %d , lines = %d ", n_chas,n_words ,n_lines );
printf("partial lines = %d \n", n_lines);
}
三木运算符
#include <stdio.h>
#define COVERAGE 200
void main()
{
int sq_feet ,cans ;
printf("Enter number of square feet to be painted :\n");
while (scanf("%d" , &sq_feet) == 1 ) {
cans = sq_feet /COVERAGE;
cans += ((sq_feet %COVERAGE == 0))? 0 : 1;
printf(" your need %d %s of paint .\n",cans ,cans == 1 ? "can " : "cans");
printf("enter next value (q to quit ) \n");
}
}
continue
#include <stdio.h>
#define COVERAGE 200
void main()
{
const float MIN = 0.0f ;
const float MAX = 100.0f;
float score ;
floattotal =0.0f;
int n = 0;
float min = MAX;
float max = min;
printf("Enter the first score (q to quit )");
while (scanf("%f",&score ) == 1) {
if (score < MIN || score > MAX) {
printf("%0.1f is an invalid value try again ", score );
continue ;
}
printf("Accepting %0.1f \n",score);
}
if (n > 0) {
printf("Average of %d scores is %0.1 f .\n",n,total/n);
printf("low = %0.1f , high = %0.1f \n ",min ,MAX);
}
else
printf(" no valid \n");
}
inu
#include <stdio.h>
#define COVERAGE 200
void main()
{
const float MIN = 0.0f ;
const float MAX = 100.0f;
float score ;
floattotal =0.0f;
int n = 0;
float min = MAX;
float max = min;
printf("Enter the first score (q to quit )");
while (scanf("%f",&score ) == 1) {
if (score < MIN || score > MAX) {
printf("%0.1f is an invalid value try again ", score );
continue ;
}
printf("Accepting %0.1f \n",score);
min = (score < min )? score : min ;
max = (score > max )? score : max;
total += score ;
n ++ ;
printf("enter netxt score (q to quit )");
}
if (n > 0) {
printf("Average of %d scores is %0.1 f .\n",n,total/n);
printf("low = %0.1f , high = %0.1f \n ",min ,MAX);
}
else
printf(" no valid \n");
}
使用break 退出循环
#include <stdio.h>
void main()
{
float lengh , width ;
printf("Length the length of the rectangle \n");
while (scanf("%f" , &lengh) == 1) {
printf("length = %0.2f",lengh);
printf("Enter its width \n");
if (scanf("%f",&width) != 1) {
break;
}
printf("Width = %0.2f \n",width);
printf("Area = %0.2f :\n ",lengh * width);
printf("enter the length of the rectangle \n");
}
printf("Done .\n");
}
GOTO 语句
#include <stdio.h>
void main()
{
int num;
float cost = 12.0;
scanf("%d",&num );
if (num > 12 ) {
goto a;
}
goto b;
a: cost = cost *1.05;
printf("cost = %f \n " , cost);
b:
printf(" this is b \n");
}
