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Basic exercises of C language for beginners
2022-07-24 01:00:00 【lhb2998658795】
1. Character inversion
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
void swap(char *a,char *b)
{
if(a==NULL&&b==NULL){
printf("The ginseng error");
exit(EXIT_SUCCESS);// For beginners, use here return ; It's OK, too , Not affecting use ;
//exit To exit this process
}
int temp=0;
while(a<b){
temp=*a;
*a=*b;
*b=temp;
a++;
b--;
}
}
void change_word(char *a)
{
char *p,*q;
p=a;
q=a+strlen(a)-1;
swap(p,q);
q=p;
// This can still be used while Realization , however while It will increase the time complexity , Use as little as possible
while(*p!=0){
if(*p!=' '){
p++;
if(*p!=0){
continue;
}
}
swap(q,p-1);
if(*p==0){
break;
}
q=(++p);
}
}
int main(int argc, char const *argv[])
{
char buff[128]={0};
printf(" Please enter what you want to enter ");
fgets(buff,sizeof(buff),stdin);// For beginners, use here gets(buff) It's OK, too , Not affecting use ;
buff[strlen(buff)-1]='\0';
change_word(buff);
printf("%s\n",buff);
return 0;
}
2. Output all less than 100 The prime number of
#include <stdio.h>>
int main(int argc, char const *argv[])
{
int n=100;
int i=0;
int j=0;
int a=0;
for(i=1;i<n;i++){
a=0;
for(j=1;j<=i;j++){
if(i%j==0){
a++;
}
}
if(a==2){
printf("%d ",i);
}
}
puts("");
return 0;
}
3 There are three ways of exchange
3.1 The first three cups of water exchange
#include <stdio.h>
int main(int argc, char const *argv[])
{
int a=10;
int b=20;
int temp=0;
temp=a;
a=b;
b=temp;
printf("a=%d b=%d\n",a,b);
return 0;
}
3.2 The second XOR Exchange
#include <stdio.h>
int main(int argc, char const *argv[])
{
int a=10;
int b=20;
int temp=0;
a=a^b;
b=a^b;
a=a^b;
printf("a=%d b=%d\n",a,b);
return 0;
}
3.3 The third exchange // Note that the value beyond the limit cannot be too large
#include <stdio.h>
int main(int argc, char const *argv[])
{
int a=10;
int b=20;
int temp=0;
b=a+b;
a=b-a;
b=b-a;
printf("a=%d b=%d\n",a,b);
4. practice ： 1. Design a program , Realization function ： Enter a character , If it's capital , Just convert it to lowercase output If it's lowercase , It is converted to uppercase output If it's a number , Just * 10 Output If it's another character , All output # a --> A B --> b 2 --> 20 ( --> #
#include<stdio.h>
int main(int argc, const char *argv[])
{
char v = 0;
scanf("%c", &v);
getchar();
if (v >= 'A' && v <= 'Z'){
v += 32;
printf("%c\n", v);
}else if (v >= 'a' && v <= 'z'){
v -= 32;
printf("%c\n", v);
}else if (v >= '0' && v <= '9'){
v -= '0';
v *= 10;
printf("%d\n", v);
}else{
printf("%c\n", '#');
}
return 0;
}5ifelse Statements use
practice ： Write a program to calculate height Every parent cares about the height of their children when they grow up , According to the knowledge of physiological health and mathematical statistics, it is shown that , There are genetic factors that affect the height of children as adults 、 Eating habits and physical exercise . The height of children as adults is closely related to their parents' height and their own gender . set up faHeight For his father's height ,moHeight For the height of his mother , The height prediction formula is ： Male adult height = (faHeight + moHeight) * 0.54(cm) Female adult height = (faHeight * 0.923 + moHeight) / 2(cm) Besides , If you love physical exercise , Then you can increase your height on the original basis 2% If you have good healthy eating habits , Then you can increase your height on the original basis 1.5% Procedural requirements ： Father's height and mother's height 、 The gender of the child 、 Do you like sports training Refining And whether there are good hygienic eating habits also input from the keyboard , The final output is predicted height . Tips ： How to input the child's gender , Prompt can be given on the screen “ Please enter the gender of the child （ Boy input 1, Girl input 0）：”, And then through if Statement to determine whether the character entered from the keyboard is 1 still 0. Whether you like physical exercise can also be achieved in a similar way .
#include <stdio.h>
int main(int argc, const char *argv[])
{
double faHeight = 0;
double moHeight = 0;
double childHeight = 0;
double pe_temp = 0,food_temp = 0;// It's used to record height
int sex = 0; // Gender 1 male 0 Woman
int PE = 0; // athletic sports 1 like 0 Don't like
int FOOD = 0;// eating habits 1 Good habit 0 I'm not used to it
printf(" Please enter your father's height :");
scanf("%lf", &faHeight);
printf(" Please enter your mother's height :");
scanf("%lf", &moHeight);
printf(" Please enter the child's gender (1 schoolboy 0 girl student ):");
scanf("%d", &sex);
if(1 == sex){
childHeight = (faHeight + moHeight) * 0.54;
}else{
childHeight = (faHeight * 0.923 + moHeight) / 2;
}
printf(" Please enter whether you like sports (1 like 0 Don't like ):");
scanf("%d", &PE);
printf(" Please enter whether you have good habits (1 Yes 0 No, ):");
scanf("%d", &FOOD);
if(1 == PE){
pe_temp = childHeight * 0.02;
}
if(1 == FOOD){
food_temp = childHeight * 0.015;
}
childHeight = childHeight + pe_temp + food_temp;
printf(" The predicted height of the child is :%.3lf\n",childHeight);
return 0;
}
6. Simple calculator implementation
. Write code , Realize the function of simple calculator ( Operands Is an integer + - * / %)： scanf("%d %c %d",); Input ：5 + 2 Output ：7 Input ：10 % 3 Output ：1
#include <stdio.h>
int main(int argc, const char *argv[])
{
int num1 = 0, num2 = 0;
char operator = 0;
scanf("%d %c %d", &num1, &operator, &num2);
switch(operator){
case '+':
printf("%d + %d = %d\n", num1, num2, num1+num2);
break;
case '-':
printf("%d ‐ %d = %d\n", num1, num2, num1-num2);
break;
case '*':
printf("%d * %d = %d\n", num1, num2, num1*num2);
break;
case '%':
printf("%d %% %d = %d\n", num1, num2, num1%num2);
break;
case '/':
printf("%d + %d = %.3lf\n", num1, num2, (double)num1/(double)num2);
break;
default:
printf(" I only support + ‐ * / %%\n");
break;
}
return 0;
}
7 Student grade management
#include <stdio.h>
int main(int argc, const char *argv[])
{
int score = 0;
scanf("%d", &score);
getchar();
switch(score/10){
case 10:
case 9:
printf("A\n");
break;
case 8:
printf("B\n");
break;
case 7:
printf("C\n");
break;
default:
printf(" fail, \n");
break;
}
return 0;
}8. Use while loop , Realization 1~100 Sum up .
#include <stdio.h>
int main(){
int i = 1, sum = 0;
while(i<=100){
sum += i;
i++;
}
printf("sum = %d\n",sum);
return 0;
}9.. Monkeys eat peaches
#include <stdio.h>
int main(){
int sum = 1;
int i = 0;
while(i<9){
printf(" The first %d God , Yes %d Peach \n", 10-i, sum);
sum = (sum+1)*2;
i++;
}
printf(" The first %d God , Yes %d Peach \n", 10-i, sum);
return 0;
}10. daffodils
#include <stdio.h>
int main(int argc, const char *argv[])
{
int i = 0;
int ge = 0;
int shi = 0;
int bai = 0;
for(i = 100; i < 1000; i++){
ge = i % 10;
shi = i / 10 % 10;
bai = i / 100;
if(ge*ge*ge + shi*shi*shi + bai*bai*bai == i){
printf("%d\n", i);
}
}
return 0;
}
11 Typesetting shows the following results
#include <stdio.h>
int main(int argc, char const *argv[])
{
char ch='A';
int i=0;
int j=0;
int a=0;
for(i=0;i<8;i++){
for(j=0;j<i-1;j++){
printf("_");
}
for(a=0;a<i;a++){
printf("%c",ch+a);
}
puts("");
}
return 0;
}12. Enter a number , Output all the factors of this number .
#include <stdio.h>
int main(int argc, const char *argv[])
{
int num = 0;
scanf("%d", &num);
getchar();
for(int i= 1; i <= num; i++){
if(num%i == 0){
printf("%d\n", i);
}
}
return 0;
}
13 Perfect number
#include <stdio.h>
int main(int argc, const char *argv[])
{
int i = 0;
int j = 0;
int sum = 0;
for(i = 1; i < 1000; i++){
sum = 0;
for(j = 1; j < i; j++){
if(i%j == 0){
sum += j;
}
}
if(sum == i){
printf("%d\n", i);
}
}
return 0;
}
13 practice ： 1. Define a 10 A length of int Array , And all initialized to 0, Loop to assign values to array members , The assigned value comes from keyboard input ; Output the largest element in the array and the subscript of the largest element .
#include <stdio.h>
int main(){
int arr[10] = {0};
int i = 0;
int max_index = 0;
for(i = 0; i < 10; i++){
scanf("%d", &arr[i]);
}
for(i = 1; i < 10; i++){
if(arr[i] > arr[max_index]){
max_index = i;
}
}
printf("max_value = %d , max_index = %d\n",arr[max_index],max_index);
return 0;
}14 Bubble sort
#include <stdio.h>
int main(int argc, const char *argv[])
{
int s[10] = {23,45,65,78,90,55,33,17,96,54};
int i = 0;
int j = 0;
int temp = 0;
int flags=0;
int len = sizeof(s)/sizeof(int);
for(i = 0; i < len; i++){
printf("%d ", s[i]);
}
printf("\n");
for(j = 0; j < len-1; j++){
flags=0;
for(i = 0; i < len-1-j; i++){
if(s[i] > s[i+1]){
temp = s[i];
s[i] = s[i+1];
s[i+1] = temp;
flags=1;
}
}
if(flags==0){
break;
}
}
for(i = 0; i < len; i++){
printf("%d ", s[i]);
}
printf("\n");
return 0;
}
15strlen function
#include <stdio.h>
int mystrlen(char *num)
{
int i=0;
while(*num){
i++;
num++;
}
return i;
}
int main(int argc, char const *argv[])
{
char num[20]="i love china";
int length=0;
length=mystrlen(num);
printf("%d\n",length);
return 0;
}16strcat
#include <stdio.h>
void mystrcat(char *dest, char *src)
{
//1. Determine whether the address is empty , If it is empty, exit
if(dest == NULL || src == NULL){
return ;
}
//2. find dest Of '\0'
while(*dest){
dest++;
}
//3. Copy the data
while(*src){
*dest++ = *src++;
}
//4. to dest Assign an end symbol
*dest = '\0';
}
int main(int argc, const char *argv[])
{
char arr[50] = {0};
char brr[100] = {0};
printf("input string (arr) > ");
gets(arr);
printf("input string (brr) > ");
gets(brr);
mystrcat(brr,arr);
printf("brr = %s\n",brr);
return 0;
}
16strcpy
#include <stdio.h>
void mystrcpy(char *dest, char *src)
{
//1. Determine whether the address is empty , If it is empty, exit
if(dest == NULL || src == NULL){
return ;
}
//2. Copy the data
while(*src){
*dest++ = *src++;
}
//3. to dest Assign an end symbol
*dest = '\0';
}
int main(int argc, const char *argv[])
{
char arr[100] = {0};
char brr[100] = {0};
printf("input string (arr) > ");
gets(arr);
mystrcpy(brr,arr);
printf("brr = %s\n",brr);
return 0;
}17strcmp
#include <stdio.h>
int mystrcmp(char *a,char *b)
{
while(*a&&*b&&*a==*b){
a++;
b++;
}
if((*a-*b)>0){
return 1;
}else if((*a-*b)<0){
return -1;
}else{
return 0;
}
}
int main(int argc, char const *argv[])
{
char a[20]={0};
char b[20]={0};
int flag=0;
printf("Please enter the value of a >");
gets(a);
printf("Please enter the value of b >");
gets(b);
flag=mystrcmp(a,b);
if(flag>0){
printf("a>b\n");
}else if(flag<0){
printf("a<b\n");
}else{
printf("a=b\n");
}
return 0;
}
18 To write atoi function
#include <stdio.h>
void my_gets(char *a,int n)
{
int i=0;
while(i<n){
if((a[i]=getchar())=='\n'){
i++;
break;
}
i++;
}
a[i]=0;
}
int my_atoi(char *s)
{
int num=0;
int sig=1;
if(*s=='-'){
sig=-1;
}
if(*s=='-'||*s=='+'){
s++;
}
while((*s)>='0'&&(*s)<='9'){
num=num*10+*s-'0';
s++;
}
return sig*num;
}
int main(int argc, const char *argv[]){
char array[50]={0};
my_gets(array,100);
printf("%d\n",my_atoi(array));
return 0;
}
19 Fibonacci sequence
#include <stdio.h>
int main(int argc, const char *argv[]){
int s[20]={1,1};
int i=0;
for(i=2;i<20;i++){
s[i]=s[i-1]+s[i-2];
}
for(i=0;i<20;i++){
printf("%d ",s[i]);
}
puts("");
return 0;
}
20 Find the maximum value in the array
#include <stdio.h>
int main(int argc, const char *argv[]){
int arr[10]={0};
int i=0;
for(i=0;i<10;i++){
scanf("%d",&arr[i]);
}
int max=0;
for(i=0;i<10;i++){
if(arr[i]>arr[max]){
max=i;
}
}
printf("%d %d\n",max,arr[max]);
return 0;
}
21 multiplication table
#include <stdio.h>
int main(int argc, char const *argv[])
{
int i=0;
int j=0;
for(i=1;i<10;i++){
for(j=1;j<=i;j++){
printf("%d*%d=%d ",j,i,i*j);
}
puts("");
}
return 0;
}
22 perpetual calendar
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int main (){
int year = 0, month = 0, day = 0;
int hour = 0, min = 0, sec = 0;
scanf("%d%d%d%d%d%d", &year, &month, &day
, &hour, &min, &sec);// When the input Space off
while(1){
system("clear");// call clear Command clear screen , Realize single line display
printf("%4d-%02d-%02d %02d:%02d:%02d\n",
year, month, day, hour, min, sec);//%02d Is to format the output Later on
sec++;
if(60 == sec){
sec = 0;
min++;
if(60 == min){
min = 0;
hour++;
if(24 == hour){
hour = 0;
day++;
//31 Day month
if(1 == month || 3 == month || 5 == month || 7 == month || 8 == month
|| 10 == month || 12 == month){
if(32 == day){
day = 1;
month++;
}
//30 Day month
}else if(4 == month || 6 == month || 9 == month || 11 == month || 8 == month){
if(31 == day){
day = 1;
month++;
}
// Leap year's 2 month
}else if((year%4==0 && year%100!=0) || year%400==0){
if(30 == day){
day = 1;
month++;
}
// In ordinary years 2 month
}else{
if(29 == day){
day = 1;
month++;
}
}
if(13 == month){
month = 1;
year++;
}
}
}
}
sleep(1);// Sleep 1 second
}
return 0;
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