一

//化简分式
#include <stdio.h>

void reduce(int numerator, int denominator, int* reduced_numerator, int* reduced_denominator);
int main()
{
    int num = 0, den = 0;
    int onum=0, oden=0;
    int* rnum=&onum, * rden=&oden;
    printf("Enter the number(n/d):");
    scanf("%d/%d", &num, &den);
    reduce(num, den, &onum, &oden);
    printf("The reduced number is:%d/%d", onum, oden);
}
void reduce(int numerator, int denominator, int* reduced_numerator, int* reduced_denominator) {
    int op = 0;
    for (int i = 1; i <= ((numerator > denominator) ? denominator : numerator); i++) {
        if (numerator % i == 0 && denominator % i == 0) {
            op = i;
        }
    }
    *reduced_numerator = numerator / op;
    *reduced_denominator = denominator / op;
}

二

数组

//判断是否是回文
#include <stdio.h>
#include <ctype.h>

int main()
{
    char in[100] = { 0 };
    int i = 0;
    while (1) {
        in[i] = getchar();
        if (in[i] == '\n')break;
        if (isalpha(in[i]) == 0) {
            continue;
        }
        else {
            in[i] = tolower(in[i]);
            i++;
        }
    }
    char op = 1;
    int b = i - 1;
    while (i) {
        if (in[i - 1] != in[b - i + 1]) {
            op = 0;
            break;
        }
        i--;
    }
    if (op == 1) {
        printf("Palindrome\n");
    }
    else {
        printf("Not a palindrome\n");
    }
}

指针

#include <stdio.h>
#include <ctype.h>

int main()
{
    char in[100] = { 0 };
    char* p=in;
    char* op = in;
    while (1) {
        *p = getchar();
        if (*p == '\n')break;
        if (isalpha(*p) == 0) {
            continue;
        }
        else {
            *p = tolower(*p);
            p++;
        }
    }
    int out = 1;
    while (p != in) {
        if (*(p - 1) != *op) {
            out = 0;
            break;
        }
        p--;
        op++;
    }
    if (out == 1) {
        printf("Palindrome\n");
    }
    else {
        printf("Not a palindrome\n");
    }
}

三

//复制指定字符串
#include <stdio.h>

int main()
{
    char in[100] = { 0 };
    char out[100] = { 0 };
    char* p=in;
    while ((*p = getchar()) != '\n')p++;
    int m, n;
    scanf("%d %d", &m, &n);
    p = in + m - 1;
    for (int i = 0; i < n; i++) {
        out[i] = *p;
        printf("%c", out[i]);
        p++;
    }
}

附加

//输入指定数量数据排序
#include <stdio.h>

void sele_sort(int in[], int i, int n);
int main()
{
    int n = 0;
    printf("Enter the number of number:");
    scanf("%d", &n);
    int* p;
    p = (int*)malloc(sizeof(int) * n);
    for (int i = 0; i < n;i++) {
        scanf("%d", &p[i]);
    }
    sele_sort(p, 0, n);
    for (int i = 0; i < n; i++) {
        printf("%d\n", p[i]);
    }
}
void sele_sort(int in[], int i, int n) {    //i为排序初始位，n为排序个数
    int j, min, t;
    if (i < n - 1) {
        min = i;
        for (j = i + 1; j < n; j++) {       //每次递归寻找从i到n个中的最小值并交换放在最前面
            if (in[j] < in[min])
                min = j;                    //记录最小值出现的位置
        }
        t = in[min];                        //交换数值
        in[min] = in[i];
        in[i] = t;
        sele_sort(in, i + 1, n);            //进入下一次递归
    }
}