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C language exercises_ one

2022-07-07 02:46:00 【51CTO】

Be careful ： Compiler uses as VS2019, Due to the compiler , The input functions of the following codes are written as scanf_s();

Calculation n The factorial .

Code ：

       
       #include<stdio.h>
       
int main(void) {
       
  int n = 0;
       
  int i = 0;
       
  int result = 1;
       
  printf(" please enter an integer n:");
       
  scanf_s("%d",&n);
       
  for (i = 0; i < n; i++) {
       
    result *= (i + 1);
       
  }
       
  printf("n! The value of is %d.\n",result);
       
  return 0;
       
}
      
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result ：

C Language exercises _1_C Language practice

Calculation 1!+2!+3!+……+10!

Code ：

       
       #include<stdio.h>
       
int main(void) {
       
  int n = 10;
       
  int i = 0;
       
  int j = 0;
       
  int result_1 = 1;
       
  int result_2 = 0;
       
  for (i = 0; i < n; i++) {
       
    for (result_1 = 1,j = 0; j < i+1; j++) {
       
      result_1 *= (j + 1);  
       
    }
       
    result_2 += result_1;
       
  }
       
  printf(" 1!+ 2!+ 3!+ …… + 10! As the result of the ：%d\n",result_2);
       
  return 0;
       
}
      
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perhaps ：（ This method is relatively simple , More efficient code ）

       
       #include<stdio.h>
       
int main(void) {
       
  int n = 10;
       
  int i = 0;
       
  int j = 0;
       
  int result_1 = 1;
       
  int result_2 = 0;
       
  for (i = 0; i < n; i++) {
       
    result_1 *= (i+1);
       
    result_2 += result_1;
       
  }
       
  printf(" 1!+ 2!+ 3!+ …… + 10! As the result of the ：%d\n",result_2);
       
  return 0;
       
}
      
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result ：

C Language exercises _1_ Loop statement _02

C Language exercises _1_C Language practice _03

Find a specific number in an ordered array n.（ Explain two-point search ）

Code ：

       
       #include<stdio.h>
       
int main(void) {
       
  int arr[] = {1,2,3,4,5,6,7,8,9};
       
  int k = 7;
       
  int left = 0;
       
  int right = sizeof(arr) / sizeof(arr[0]) - 1;
       
  int mid = (left + right) / 2;
       
  while (left <= right) {
       
    if (arr[mid] == k) {
       
      printf("%d The subscript of is %d.", k, mid);
       
      break;
       
    }
       
    else if (arr[mid] > k) {
       
      right = mid - 1;
       
      mid = (left + right) / 2;
       
    }
       
    else if (arr[mid] < k) {
       
      left = mid + 1;
       
      mid = (left + right) / 2;
       
    }
       
  }
       
  if (left > right) {
       
    printf("%d Not in array .",k);
       
  }
       
  return 0;
       
}
      
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result ：

C Language exercises _1_ Loop statement _04

Write code , Demonstrate the movement of multiple characters from both ends , Converging in the middle .

Code ：

       
       #include<stdio.h>
       
#include<string.h>
       
int main(void) {
       
  char arr[] = "Welcome to China!!!!!!";
       
  int left = 0;
       
  int right = strlen(arr) - 1;
       
  int i;
       
  while (left <= right) {
       
    for (i = 0; i < strlen(arr); i++) {
       
      if (i <= left || i >= right)
       
        printf("%c", arr[i]);
       
      else
       
        printf("#");
       
    }
       
    printf("\n");
       
    left++;
       
    right--;
       
  }
       
  return 0;
       
}
      
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result ：

C Language exercises _1_ Loop statement _05

Write code to achieve , Simulate user login scenarios , And can only log in three times .（ Only three passwords are allowed , If the password is correct Prompt to log in as , If all three inputs are wrong , Then exit the program .

Code ：

       
       #include<stdio.h>
       
#include<string.h>
       
int main(void) {
       
  char arr[] = "abc";
       
  char password[20]="0";
       
  int i = 0;
       
  for (i = 0; i < 3; i++) {
       
    printf(" Please input a password ：");
       
    scanf_s("%s", password,10);
       
    if (strcmp(password, arr) == 0) {
       
      printf(" Confirm password successfully ！\n");
       
      break;
       
    }
       
    else {
       
      printf(" Confirm password failed , Please try again ！\n");
       
    }
       
  }
       
  if (3 == i) {
       
    printf("3 Failed to confirm the password for times , Please try again later ！\n");
       
  }
       
  return 0;
       
}
      
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