C language 005: common examples

3、 ... and 、 Program analysis questions

1、 When a=1,b=3,c=5,d=4 when , After executing the following procedure x What's the value of ？

#include<stdio.h>

void main()
{
    
    int a=1,b=3,c=5,d=4,x;
    if(a<b)
        if(c<d)
        x=1;
    else if (a<c)
        if(b<d) x=2;
    else x=3;
    else x=6;
    else x=7;
    printf("%d",x);
    return ;
}

answer ：2

2、 For the following recursive functions f, call f(4), Its return value is ？

#include<stdio.h>

void main()
{
    
    printf("%d",f(4));
    return ;
}

int f(int n)
{
    
    if(n>=1) return f(n-1)+n;
    else return n;
}

answer ：10

3、 When performing the following procedure , If input abc, Then the output of the following program is ？

#include<stdio.h>

void main()
{
    
    char s[20]="12345";
    scanf("%s",s);
    strcat(s,"6789");
    printf("%s\n",s);
    return ;
}

answer ：abc6789

4、 The output of the following program is ？

#include<stdio.h>

void main()
{
    
    int a[6]={
    1,2,3,4,5,6},i,s=0;
    for(i=0;i<6;i++)
        s+=a[i];
    printf("%d\n",s);
    return ;
}

answer ：21

Four 、 Calculation questions

1、 Through the bubble sorting algorithm on the array int a[8] ={25,24,12,76,101,96,28,-1} Sort , requirement ： Draw the first trip 、 The state of the array after the second sorting .

Refer to the answer ：

2、 Use the half search method in the integer sequence ｛-1, 3 ,5 ,6 , 8 ,12, 32, 56, 85, 95, 100｝ Find the number in 10, Try to draw a picture, analyze and find the process .

Refer to the answer ：

5、 ... and 、 Programming problem

1、 Programming questions . Enter a character , Judge whether it is a capital letter 、 Lowercase letters 、 Numbers or other .

Refer to the answer ：

#include<stdio.h>

int main()
{
    
    char ch;
    while((ch=getchar())!=EOF){
    
        if(ch>='A'&& ch<='Z')
            printf(" It's capital letters ！\n");
        else if(ch>='a'&& ch<='z')
            printf(" It's lowercase ！\n");
        else if(ch >='0'&& ch<='9')
            printf(" It's the number. ！\n");
        else
            printf(" It's something else ！\n");
        getchar();
    }
    return ;
}

2、 Programming questions . Input from keyboard 10 Number , Output its minimum and maximum values .

#include<stdio.h>

int main()
{
    
    int arr[10];
    int i,max,min;
    for(i=0;i<10;i++)
        scanf("%d",&arr[i]);
    max=arr[0];
    min=arr[0];
    for(i=1;i<10;i++){
    
        if(arr[i]>max)
            max=arr[i];
        if(arr[i]<min)
            min=arr[i];
    }
    printf(" minimum value ：%d, Maximum ：%d\n",min,max);
    return 0;
}

3、 Programming questions . Write a function to determine prime numbers , stay main The function is called in the function , Output 100 All prime numbers within .

Refer to the answer ：

#include<stdio.h>

int su_shu(int n){
    
    int i;
    if(n==1)
        return 0;
    for(i=2;i<=n;i++){
    
        if(n%i==0&&n!=i)
            return 0;
        if(n==i)
            return 1;
    }
}


int main()
{
    
    int i;
    for(i=1;i<100;i++){
    
        if(su_shu(i)==1)
            printf("%d\t",i);
    }
    return 0;
}

4、 Programming questions . Write function mystrcmp（ The formal parameter is a pointer ）, Used to determine the greater than... Between two strings 、 Less than or equal to .

Refer to the answer ：

#include<stdio.h>

int mystrcmp(const char *str1,const char *str2){
    
    while(*str1==*str2)
    {
    
        if(*str1=='\0'&&*str2=='\0')
            return 0;
        str1++;
        str2++;

    }
    if(*str1>*str2)
        return 1;
    if(*str1<*str2)
        return -1;
}


int main()
{
    
    char str1[100],str2[100];
    scanf("%s",str1);
    scanf("%s",str2);
    int i=mystrcmp(str1,str2);
    if(i==0)
        printf(" String equality \n");
    if(i==1)
        printf(" character string 1 Greater than string 2\n");
    if(i==-1)
        printf(" character string 1 Less than string 2\n");

    return 0;
}