string源代码.docx

String类源代码一.C字符串1. strlen(),计算字符串长度 int strlen(const char string) int i=0; while(stringi) i+; return i; 2. strcpy(), 字符串拷贝. char *strcpy(char *destination, const char *source) while(*destinaton+=*source+); return (destination-1); 3. strcat(), 字符串的连接. char *strcat(char *target,const char *source) char *original=target; while(*target) target+; / Find the end of the string while(*target+=*source+); return(original); 4. streql(), 判断两个字符串是否相等. int streql(char *str1,char *str2) while(*str1=*str2)&(*str1) str1+; str2+; return(*str1=NULL)&(*str2=NULL); 5. strchr(), 在字符串中查找某个字符. char *strchr(const char *string,int letter) while(*string!=letter)&(*string) string+; return (string); 6. chrcnt(), 计算某个字符在字符串中出现的次数. int chrcnt(const char *string,int letter) int count=0; while(*string) if(*string=letter)count+; return count; 7. strcmp(), 判断两个字符串是否相等. int strcmp(const char *str1,const char *str2) while(*str1=*str2)&(*str1) str1+; str2+; if(*str1=*str2)&(!*str1) /Same strings return o; else if(*str1)&(!*str2) /Same but str1 longer return -1; else if(*str2)&(!*str1) /Same but str2 longer else return(*str1*str2)?-1:1); 二. String类1 int size(string str)/return the size of a stringint count = 0;while(strcount)count+;return count;2 bool empty(string str)/check whether a string is empty or notbool empty = false;if(size(str) = 0)empty = true;return empty;3 int find1(string str, char a, int index)/return the index of a specific character begin from the start index/如果index =0，直接初始化i = 0int i = index;while(i = 0)if(stri = a)break;i-;return i;5 int find3(string str, string aa)/查一个string, 返回index/若有startindex，则初始化i = startindexint index;for(int i = 0; i str.size(); i+)if(stri = aa0)int m = i;int n = 0;bool check = true;for(/*int m = i, int n = 0*/; m str.size(), n aa.size(); m+, n+)if(strm != aan)check = false;break;if(check)index = i;break;return index;6 string substring(string str, int index, int length)/return a substring from the startindex/若限制长度，则i index + lengthstring substring;for(int i = index; i str.size(); i+)substring.push_back(stri);return substring;7 string append(string str, string a)/追加字符串for(int j = 0; j a.size(); j+)str.push_back(aj);return str;8 string erase(string str, int index, int length)string temp;for(int i = 0; i index; i+)temp.push_back(stri);for(int i = index + length; i str.size(); i+)temp.push_back(stri);str = temp;return str;9 string clear(string str)string temp = ;str = temp;return str;10 void pushback(string &str, char a)/append a characterstr = str + a;11 string insert(string str, int index, string a)/insert a stringstring result;for(int i = 0; i index; i+)result.push_back(stri);result += a;for(int i = index; i str.size(); i+)result.push_back(