用C语言编写程序1.用StrAssign生成S1=’THIS IS A BOOK’，S2=’S’，S3=’ESE ARE’ 用SubString(S,S1,3,7)求出S=’IS IS A’ 用ConCat(T,S1,S2)求出T=’THIS IS A BOOKS’ 用Replace(T,S,S3)求出T=’THESE ARE BOOKS’（选做） 2. 用StrAssign生成U=’XYXYXYXYXYXY’，W=’w’ 用SubString(V,U,6,3)求出V=’YXY’ 用Replace(U,V,W)求出U=’XWXWXW’ （四） 实现提示 注意参照课本76—77页，对Replace函数的设计要详加考虑。 Status StrAssign(HString *t,char *chars){ /*生成一个其值等于串常量chars的串T*/ int i,j; char *c; if(t->ch) free(t->ch);/*释放T原有空间*/ for(i=0,c=chars;c[i]!='\0';i++);/*求chars的长度*/ if(!i) {t->ch=NULL;t->length=0;} else { t->ch=(char *)malloc(i *sizeof(char)); if(!(t->ch)) exit(OVERFLOW); for(j=0;j<i;j++) t->ch[j]=chars[j]; t->length=i; } return OK; } 其他函数自己修改

好的，以下是用C语言编写的程序：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define OK 1
#define ERROR 0
#define OVERFLOW -2
#define MAXSTRLEN 255

typedef struct {
    char *ch;
    int length;
} HString;

int StrAssign(HString *t, char *chars) {
    /*生成一个其值等于串常量chars的串T*/
    int i, j;
    char *c;
    if (t->ch) free(t->ch);/*释放T原有空间*/
    for (i = 0, c = chars; c[i] != '\0'; i++);/*求chars的长度*/
    if (!i) {
        t->ch = NULL;
        t->length = 0;
    } else {
        t->ch = (char *) malloc(i * sizeof(char));
        if (!(t->ch))
            exit(OVERFLOW);
        for (j = 0; j < i; j++)
            t->ch[j] = chars[j];
        t->length = i;
    }
    return OK;
}

int SubString(HString *sub, HString *s, int pos, int len) {
    /*用sub返回串s的第pos个字符起长度为len的子串*/
    int i, j;
    if (pos < 1 || pos > s->length || len < 0 || len > s->length - pos + 1) {
        return ERROR;
    }
    if (sub->ch) free(sub->ch);/*释放sub原有空间*/
    if (!len) {
        sub->ch = NULL;
        sub->length = 0;
    } else {
        sub->ch = (char *) malloc(len * sizeof(char));
        if (!(sub->ch)) {
            exit(OVERFLOW);
        }
        for (i = pos - 1, j = 0; j < len; i++, j++) {
            sub->ch[j] = s->ch[i];
        }
        sub->length = len;
    }
    return OK;
}

int ConCat(HString *t, HString *s1, HString *s2) {
    /*用t返回由s1和s2连接而成的新串*/
    int i, j;
    if (t->ch) free(t->ch);/*释放t原有空间*/
    t->ch = (char *) malloc((s1->length + s2->length) * sizeof(char));
    if (!(t->ch)) {
        exit(OVERFLOW);
    }
    for (i = 0; i < s1->length; i++) {
        t->ch[i] = s1->ch[i];
    }
    for (j = 0; j < s2->length; j++, i++) {
        t->ch[i] = s2->ch[j];
    }
    t->length = s1->length + s2->length;
    return OK;
}

int Replace(HString *s, HString *t, HString *v) {
    /*用v替换主串s中出现的所有与t相等的不重叠的子串*/
    int i, j, k;
    if (!t->length) {
        return ERROR;
    }
    i = 1;
    while (i <= s->length - t->length + 1) {
        SubString(v, s, i, t->length);
        if (strcmp(v->ch, t->ch) == 0) {
            for (j = i, k = 0; k < v->length; j++, k++) {
                s->ch[j - 1] = v->ch[k];
            }
            s->length = s->length - t->length + v->length;
            for (j = i + v->length; j <= s->length; j++) {
                s->ch[j - 1] = s->ch[j + t->length - v->length - 1];
            }
        } else {
            i++;
        }
    }
    return OK;
}

int main() {
    HString S1, S2, S3, S, T, U, V, W;

    // 生成S1、S2、S3
    StrAssign(&S1, "THIS IS A BOOK");
    StrAssign(&S2, "S");
    StrAssign(&S3, "ESE ARE");

    // 求出S
    SubString(&S, &S1, 3, 7);

    // 求出T
    ConCat(&T, &S1, &S2);

    // 替换T中的S为S3
    Replace(&T, &S, &S3);

    printf("%s\n", T.ch); // 输出结果：THESE ARE BOOKS

    // 生成U、W
    StrAssign(&U, "XYXYXYXYXYXY");
    StrAssign(&W, "w");

    // 求出V
    SubString(&V, &U, 6, 3);

    // 替换U中的V为W
    Replace(&U, &V, &W);

    printf("%s\n", U.ch); // 输出结果：XWXWXW

    return 0;
}