定长顺序串的基本操作

#define _CRT_SECURE_NO_WARNINGS//解决vs下scanf报错
#include <stdio.h>
#include <stdlib.h>
#define MAXLEN 5

typedef struct
{
    char ch[MAXLEN];
    int len;
}SString;//selected length string

void Get(SString* str);
void Put(SString* str);
void Insert(SString* strA, int pos, SString* strB);
void Delete(SString* strA, int pos, int len);
void Cat(SString* strA, const SString strB);
void Sub(const SString strA, SString* strB, int pos, int len);//求子串

int main(void)
{
    int pos;//插入字符串位置
    int len;//删除字符串长度
    SString strA = {"", 0};
    SString strB = {"", 0};

    Get(&strA);
    Put(&strA);
    Get(&strB);
    Put(&strB);
    
    printf("请输入要插入字符串的位置:\n");
    scanf("%d", &pos);
    Insert(&strA, pos, &strB);
    Put(&strA);

    printf("请输入要删除字符串的位置和长度(以逗号分割)\n");
    scanf("%d,%d", &pos, &len);
    Delete(&strA, pos, len);
    Put(&strA);

    printf("正在连接两个字符串:\n");
    Cat(&strA, strB);
    Put(&strA);

    printf("请输入子串在主串的位置和长度(逗号分隔)\n");
    scanf("%d,%d", &pos, &len);
    Sub(strA, &strB, pos, len);
    Put(&strB);

    system("pause");
    return 0;
}

void Get(SString* str)
{
    int x;
    printf("请输入一串字符:\n");
    while ((x = getchar()) != '\n')
    {
        if (str->len > MAXLEN - 1)
        {
            printf("串空间已满，已截断!\n");
            while ((x = getchar()) != EOF && x != '\n');//清空缓存区
            break;
        }
        str->ch[(str->len++)] = x;
    }
}

void Put(SString* str)
{
    int i;
    printf("len:%d\t", str->len);
    printf("str:");
    for (i = 0; i < str->len; i++)
    {
        printf("%c", str->ch[i]);
    }
    printf("\n");
}

void Insert(SString* strA, int pos, SString* strB)
{
    int i;
    if (pos < 1 || pos > MAXLEN)
    {
        printf("\n插入位置不合法!\n");
        exit(-1);
    }

    pos = pos - 1;//字符串数组下标从0开始
    if (strA->len + strB->len <= MAXLEN)//插入后串长小于MAXLEN
    {
        for (i = strA->len + strB->len; i > pos + strB->len -1; i--)//插入后
        {
            strA->ch[i] = strA->ch[i - strB->len];
        }
        for (i = pos; i < pos + strB->len; i++)//插入部分
        {
            strA->ch[i] = strB->ch[i - pos];
        }
        strA->len = strA->len + strB->len;
    }
    else if (pos + strB->len <= MAXLEN)//插入后串长大于MAXLAN，串B可以全部插入
    {
        for (i = MAXLEN - 1; i > pos + strB->len - 1; i--)
        {
            strA->ch[i] = strA->ch[i - strB->len];
        }
        for (i = pos; i < pos + strB->len; i++)
        {
            strA->ch[i] = strB->ch[i - pos];
        }
    }
    else//插入后串长大于MAXLAN，串B的部分字符也可能被舍弃
    {
        for (i = pos; i < MAXLEN; i++)
        {
            strA->ch[i] = strB->ch[i - pos];
        }
    }
}

void Delete(SString* strA, int pos, int len)
{
    int i;
    if (pos < 1 || pos > strA->len || len < 1 || len > strA->len - pos + 1)
    {
        printf("\n删除参数不合法!\n");
        exit(-1);
    }
    pos = pos - 1;//字符串数组下标从0开始
    for (i = pos; i <= strA->len - len; i++)
    {
        strA->ch[i] = strA->ch[i + len];
    }
    strA->len = strA->len - len;
}

void Cat(SString* strA, const SString strB)
{
    int i;
    if (strA->len + strB.len <= MAXLEN)//连接后串长不大于MAXLEN
    {
        for (i = strA->len; i < strA->len + strB.len; i++)
        {
            strA->ch[i] = strB.ch[i - strA->len];
        }
        strA->len = strA->len + strB.len;
    }
    else if (strA->len < MAXLEN)//连接后串长大于MAXLEN，且串A的长度小于MAXLEN,串B的部分字符被舍弃
    {
        for (i = strA->len; i < MAXLEN; i++)
        {
            strA->ch[i] = strB.ch[i - strA->len];
        }
        strA->len = MAXLEN;
    }
    else//串A的长度等于MAXLEN，串B不被连接
    {
        ;
    }
}

void Sub(const SString strA, SString* strB, int pos, int len)
{
    int i;
    if (len < 1 || len > strA.len - pos + 1 || pos < 1 || pos > strA.len)
    {
        printf("\n求子串参数不合法!\n");
        exit(-1);
    }
    pos = pos - 1;//字符串数组下标从0开始
    for (i = 0; i < len; i++)
    {
        strB->ch[i] = strA.ch[pos + i];
    }
    strB->len = len;
}