Question

我想弄清楚如何首先修改我的quicksort程序以使用指针算术，然后将我的bubblesort程序更改为使用指针的递归程序，最后将这两个程序实现到计算器（calc.c）程序中。我将按照提及的顺序发布我的代码。

快速排序：

#include <stdio.h>

#define N 10
void quicksort(int a[], int low, int high);
int split(int a[], int low, int high);
int main(void)
{
    int a[N], i;
    printf("Enter %d numbers to be sorted: ", N);
    for (i = 0; i < N; i++)
        scanf("%d", &a[i]);
    quicksort(a, 0, N - 1);
    // bubblesort(a, 0, N-1);
    printf("In sorted order: ");
    for (i = 0; i < N; i++)
        printf("%d ", a[i]);
    printf("\n");
    return 0;
}

void quicksort(int a[], int low, int high)
{
    int middle;
    if (low >= high) return;
    middle = split(a, low, high);
    quicksort(a, low, middle - 1);
    quicksort(a, middle + 1, high);
}

int split(int a[], int low, int high)
{
    int part_element = a[low];
    for (;;) {
        while (low < high && part_element <= a[high])
            high--;
        if (low >= high) break;
        a[low++] = a[high];
        while (low < high && a[low] <= part_element)
            low++;
        if (low >= high) break;
        a[high--] = a[low];
    }
    a[high] = part_element;
    return high;
}

冒泡：

void bubblesort(int a[], int low, int high)
{
    int i, j, temp;
    for (j = high; j > low; j--) {
        for (i = low+1; i <= j;i++) {
            if (a[i] < a[i-1]) {
                temp=a[i];a[i]=a[i-1];a[i-1]=temp;
            }
        }
    }
}

Calc.c：

/**  To compile this code, use                         **
 *  gcc -o calc calc.c -std=c99 -lm                    **/

#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <stdbool.h>
#define KEY "Enter the calculator operation you want to do: "
#define enter_option() printf("%s", KEY)

#define SCREEN_HEIGHT 15
#define clear_screen() \
for ( int i = 0; i < SCREEN_HEIGHT; i++ ) printf("\n");

#define clean_input() while ((getchar())!='\n') continue;

#define calculator_operations() printf("\n"); \
printf("********    Welcome to C calculator     ***********\n"); \
printf("**-----------------------------------------------**\n"); \
printf("**   Press 'Q' or 'q' to quit the program        **\n"); \
printf("**   Press 'H' or 'h' to display below options   **\n"); \
printf("**   Press 'C' or 'c' to clear the screen        **\n"); \
printf("**-----------------------------------------------**\n"); \
printf("**   Enter 'A' or 'a' for arithmetic mode        **\n"); \
printf("**   Enter 'F' or 'f' for function mode          **\n"); \
printf("**   Enter 'S' or 's' for sorting mode           **\n"); \
printf("***************************************************\n"); \
printf("\n");

#define DISP(f,x) printf(#f"(%g) = %g\n",x,f(x));
#define DISP_I(f,x) printf(#f"(%d) = %d\n",(int) x,(int) f((int) x));

// Function prototype declaration
void arith_mode();
void func_mode();
void sort_mode();
void read_line(char *);
int factorial(int );

// Start of Main Program
int main()
{
    int X=1;
    char Calc_Mode;

    do
    {
        calculator_operations();
        enter_option();
        Calc_Mode=getchar();

        switch(Calc_Mode)
        {
            case 'A': case 'a': arith_mode(); break;
            case 'F': case 'f': func_mode(); break;
            case 'S': case 's': sort_mode(); break;
                // Can you integrate the quick sort program into our calculator?

            case 'H': case 'h': case '\n': break;

            case 'Q': case 'q': printf("Leaving Calculator!\n");
                exit(0);

            case 'C': case 'c': clear_screen();
                clean_input(); break;
        }

    } while (X);
}

//Function Definitions

void arith_mode()
{
    double value, operand;
    char operator;

    printf("\nPlease enter arithmetic expression "
           "as in \"x +-*/%%^ y +-*/%%^ z ...\" \n");
    printf("Your expression is: ");

    /* Read first operand */
    scanf("%lf", &value);

    /* Read successive operators and operands */
    while ((operator = getchar()) != '\n') {
        if (operator == ' ') continue;

        scanf("%lf", &operand);
        switch (operator) {
            case '+': value += operand; break;
            case '-': value -= operand; break;
            case '*': value *= operand; break;
            case '/': value /= operand; break;
            case '%': value = ((int) value)%((int) operand); break;
            case '^': value = pow(value,operand); break;
            default:  printf("\n Invalid Operator! \n"); exit(0);
        }
    }

    /* Print result */
    printf("Value of expression: %g\n\n", value);
}

void func_mode()
{
    char *cp, func_initial, line[40];
    double variable;

    printf("\nPlease enter functions as in "
           "\"name(x)\". \n");
    printf("Your function is: ");

    clean_input();

    read_line(line);
    func_initial = line[0];

    for (cp = line; *cp; cp++) {
        if (*cp == '(') {
            sscanf(++cp,"%lf", &variable);
            switch (func_initial) {
                case 'F': case 'f': DISP_I(factorial,variable); break;
                case 'E': case 'e': DISP(exp,variable); break;
                case 'S': case 's': DISP(sqrt,variable); break;
                default: printf("\n Invalid Function! \n"); exit(0);
            }
            break;
        }
    }
}

void sort_mode()
{
    clean_input();
    printf("\nComing Attraction!!!\n");
    printf("We'll integrate the quicksort program into our calculator!!!\n\n");
}

void read_line(char *line)
{
    int index; char ch;

    index = 0;
    while ((ch= getchar()) !='\n') {
        if (ch == ' ') continue;
        line[index++] = ch;
    }

    line[index] = '\0';
}

int factorial(int n)
{
    if(n<=1) return 1;
    else return n*factorial(n-1);
}

Answer 1

基于指针的快速排序标题应如下所示：

void quicksort(int * low, int * high)
{
int * middle = low + ((high-low)/2);
/* ... */

使用指针的Quicksort和Bubblesort，将这两者都实现为calc.c

1 个答案: