串的基本操作

#include <stdlib.h>
#include <iostream>
#include <stdio.h>
#define MaxSize 255typedef struct{char ch[MaxSize];int length;
}SString;//初始化
SString InitStr(SString &S){S.length=0;return S;
} //为了方便计算，串的下标从1开始计算 
//给串赋值 
SString SetStr(SString &S){char c;int i=1;scanf("%c",&c);while(c!='\n'){S.ch[i++]=c;S.length++;scanf("%c",&c);}return S;
} //返回字符串的长度
int StrLength(SString &S){return S.length;
} //清空字符串 
void ClearStrinf(SString &S){S.length=0;
}//求字符串的字串
bool SubString(SString &Sub,SString &S,int pos,int len){if(pos+len-1>S.length) return false;//字串超出范围for(int i=pos;i<pos+len;i++){Sub.ch[i-pos+1] = S.ch[i];} Sub.length = len;return true;
} //比较字符串
bool StrCompare(SString &S,SString &T){for(int i=1;i<=S.length && i<=T.length;i++){if(S.ch[i]!=T.ch[i])//进行字符比较 return S.ch[i]-T.ch[i];// S>T:>0,S<T:<0,S=T:=0 }return S.length-T.length;//所有字符都相同，长度大的串更大 
} //定位操作
int Index(SString &S,SString &T){int i=0;int n=StrLength(S);int m=StrLength(T);SString Sub;//暂时存字串 while(i<=n-m+1){SubString(Sub,S,i,m);if(StrCompare(Sub,T)!=0) i++;else return i;//返回字串在主串的位置 }return 0;//不存在与T匹配的字串 
}//显示串 
void ShowString(SString &S){for(int i=1;i<S.length;i++){printf("%c",S.ch[i]);}printf("\n");
}int main(){printf("设置串:");SString S;InitStr(S);SetStr(S);int len1;len1=StrLength(S);printf("串长度为:%d\n",len1);printf("设置字串:");SString D;InitStr(D);SetStr(D);int len2;len2=StrLength(D);printf("子串长度为:%d\n",len2);printf("\n");printf("-----------求字符串的字串-------------\n");SString Sub;int pos,len;printf("输入截取的起始位置和长度:");scanf("%d,%d",&pos,&len);if(SubString(Sub,S,pos,len)) {printf("截取后的字串\n");ShowString(Sub);}else printf("截取失败\n");printf("\n");printf("-------------定位字串-------------\n");int i;i=Index(S,D);if(i) printf("字串定位:%d",i);else printf("字串定位失败\n");return 0;
}

展示