linux下c/c++实例之八字符串分隔、去空格和转大小写

一、简介

      Linux下对字符串的操作使用频率高，在此总结部分功能。其中包括字符串的特征字符的分割、字符串左右边缘空格的去除（也可去掉左右特征字符串）及字符串大小转换。

二、详解

1、字符串分隔

（1）strtok.cpp：

#include <iostream>#include <string>#include <vector>#include <list>#include <string.h>#include <stdio.h>#include <stdlib.h>using namespace std;//字符分隔void string_to_array(const string& source, char delimiter, vector<string>& the_vector){    string dest = "";    int i;    the_vector.resize(0);    for (i = 0; i < source.length(); i++) {        if (source[i] != delimiter)  dest += source[i];        else {            if (dest.empty() == false) {   //不为空                the_vector.push_back(dest);                dest = "";            }        }    }    if (dest.empty() == false) the_vector.push_back(dest);}void chars_to_vector(char *str, char *delimiter, vector<string> &result){    int i;    string dest = "";    for(i = 0; i < strlen(str); i++) {        if (memcmp(&str[i], delimiter , strlen(delimiter)) == 0) {  //找到            result.push_back(dest);            i = i + 1;     //skip delimiter, i++ will skip one            dest = "";        }        else {            dest += str[i];        }    }    if (dest != "")  result.push_back(dest);}void chars_to_list(const char *str, const char split, list<string>& lstr){    char buff[1024] = {0};    char tmp[100] = {0};    char *pch = NULL;    bool bFound = false;    strcpy(buff, str);    while(1) {        pch = strchr(buff, split);        if (pch == NULL) {            break;        }        bFound = true;        memset(tmp, 0, sizeof(tmp));        strncpy(tmp, buff, pch - buff);        tmp[pch - buff] = '\0';        lstr.push_back(tmp);        strcpy(buff, pch + 1);    }    if ( ( bFound == true) || (strlen(buff) > 0) ) {        lstr.push_back(buff);    }}void chars_to_chars(char *str, char delm, char array[][20]){    char *p = str;    char *q = NULL;    int num;    int count = 0;    while(1) {        if (p[0] == '\0')  break;        else {            q = p;            num = 0;            while ((q[0] != delm) &&(q[0] != '\0')) {                num ++;                q ++;            }            strncpy(array[count], p, num);            count++;            p = q;            p ++;        }    }}/***使用strtok_r多个分隔符,.|分隔****/void chars_to_strtok(char *stok_char, const char *stok_delm, vector<string> &v_result){    char *str = (char *)malloc(strlen(stok_char) + 1);    memset(str, 0, strlen(stok_char) + 1);    strcpy(str, stok_char);    char *result = NULL;    char *p_tmp = NULL;    result = strtok_r(str, stok_delm, &p_tmp);    while(result != NULL) {        v_result.push_back(result);        result = strtok_r(NULL, stok_delm, &p_tmp);    }}int main(){    /************单个字符分隔**************/    string str = "ac d, ddd,ccc";    char delimiter = ',';    vector<string> final;    string_to_array(str, delimiter, final);    for(int i = 0; i < final.size(); i++) {        cout<<final[i]<<endl;    }    /************多个字符分隔**************/    char source[] = "name e|.num|.money";    char delm[] = "|.";    vector<string> out;    chars_to_vector(source, delm, out);    for(int i = 0; i < out.size(); i++) {        cout<<out[i]<<endl;    }    /***********单个字符分隔另一种方式************/    cout<<"***************chars to list***************"<<endl;    char list_str[] = "ac d, ddd,ccc";    char list_sep = ',';    list<string> lstr;    chars_to_list(list_str, list_sep, lstr);    list<string>::iterator it;    for ( it=lstr.begin(); it != lstr.end(); it++ ) {        cout<<*it<<endl;    }    cout<<"****************************"<<endl;    char to_char[] = "ao,yang,de,di,pan";    char to_delm = ',';    char to_array[10][20] = {0};    chars_to_chars(to_char, to_delm, to_array);    for(int i = 0; i < 10, strlen(to_array[i]) > 0; i++)  cout<<to_array[i]<<endl;    cout<<"****************************"<<endl;    char stok_char[] = "ao,yang.de,di|pan";    char stok_delm[] = ",.|";    vector<string>v_result;    chars_to_strtok(stok_char, stok_delm, v_result);    for(int i = 0; i < v_result.size(); i++)  cout<<v_result[i]<<endl;    return 0;}

（2）编译运行

g++ -o scanfile scanfile.cpp ./scanfile

2、字符串去特征字符（空格等）

（1）trim.cpp：

#include <iostream>#include <algorithm>#include <string>#include <string.h>using namespace std;/***去掉string中单个字符***/void string_trim(string &str, const char ch){    string::iterator it;    for (it = str.begin(); it < str.end(); it++) {        if (*it == ch) {            str.erase(it);            it--;        }    }}/***去掉字符的左边的空格或其他字符***/void ltrim(char *str, const char ch){    char *ptr;    for (ptr = str; *ptr; ptr++) {        if(*ptr != ch)  break;    }    strcpy(str, ptr);}/***去掉字符的右边的空格或其他字符***/void rtrim(char *the_str, const char ch){    int i;    int len = strlen(the_str);    for (i = len - 1; i >= 0; i--) {        if (the_str[i] != ch)  break;    }    the_str[i + 1] = '\0';}/***去掉字符左边顺序的多个字符***/void ltrim(char* the_str, const char* fill){    char *ptr = the_str;    while (strncmp(ptr, fill, strlen(fill)) == 0) {  //相等        ptr += strlen(fill);    }    if (ptr != the_str)  strcpy(the_str, ptr);}/***去掉字符右边顺序的多个字符***/void rtrim(char* the_str, const char* fill){    char *p = the_str + strlen(the_str) - strlen(fill);    cout<<"p="<<p<<endl;    while(strncmp(p, fill, strlen(fill)) == 0 && p >= 0) { //匹配        p = p - strlen(fill);        cout<<p<<endl;    }    int len = p - the_str + strlen(fill);    the_str[len] = '\0';}/***fill指包含多个不同字符,可以是不连续的***/void ltrim_leap(char* the_str, const char* fill){    char* ptr;    for (ptr = the_str; *ptr; ptr++) {        if(!strchr(fill, *ptr))  break;    }    strcpy(the_str, ptr);}/***fill指包含多个不同字符,可以是不连续的***/void rtrim_leap(char* the_str, const char* fill){    int i;    int len = strlen(the_str);    for (i = len - 1; i >= 0; i--) {        if(!strchr(fill, the_str[i]))  break;    }    the_str[i + 1] = '\0';}/***综上可以构成略去左右空格函数***/void trim(char* the_str, const char ch){    rtrim(the_str, ch);    ltrim(the_str, ch);}int main(){    cout<<"**************"<<endl;    string str = "ao&yang";    char ch = '&';    string_trim(str, ch);    cout<<str<<endl;    char data[] = "   aoa yang !ao  ";    char ch_d = ' ';    ltrim(data, ch_d);    rtrim(data, ch_d);    cout<<"data:"<<data<<endl;    ltrim(data, "ao");    rtrim(data, "!ao");    cout<<data<<endl;    cout<<"**************"<<endl;    return 0;}

（2）编译运行：

g++ -o trim trim.cpp ./trim

3、字符串大小写转换

（1）部分代码

#include <iostream>#include <string>#include <string.h>#include <stdarg.h>using namespace std;void upper(char *str){  for (char *ptr = str; *ptr != '\0'; ptr++) {    *ptr = toupper(*ptr);  }}void upper(string& the_str){  for (int i  = 0 ; i < the_str.size(); i++ ) {    the_str[i] = toupper( the_str[i] );  }}void lower(char* the_str){  for (char* ptr = the_str; *ptr; ptr++) {    *ptr = tolower(*ptr);  }}void lower(string& the_str){  for (int i  = 0 ; i < the_str.size(); i ++ ) {    the_str[i] = tolower( the_str[i] );  }}

4、字符串其他操作

（1）字符串替换

/***凡是在字符串中的字符全部替换掉***/void replace(char* the_str,char *oldchs,char newch){  for (char* ptr = the_str; *ptr; ptr++) {    if (strchr(oldchs,*ptr)) {      *ptr = newch;    }  }}

（2）格式化变长参数

void writeLog(char* section, const char* format, ...){  char t_format[81920];  memset(t_format, 0, sizeof(t_format));  va_list vl_fmt;      //参数列表  va_start(vl_fmt, format);  vsprintf(t_format, format, vl_fmt);    //格式化处理format到字符串buf_Format  va_end(vl_fmt);}

（3）变长参数处理

/***把变长参数格式化到字符串***///此函数未理解,以后运用时再加以熟悉int super_sscanf(const char *buf,char sp,const char *fmt,...)  //sp分隔符{  va_list arglist;  int   value_type;  int   is_format;  int   is_token;    va_start(arglist,fmt);  is_format = 0;  is_token = 0;  while(1)  {    if (*fmt == '%')    {      is_format ++;    }    else if (*fmt == 's' || *fmt == 'S')    {      value_type = 0;      is_token ++;    }    else if (*fmt == 'd' || *fmt == 'd' || *fmt == 'i' || *fmt == 'i')    {      is_token ++;      value_type = 1;    }    else if (*fmt == 'c' || *fmt == 'C')    {      value_type = 2;      is_token ++;    }    else if (*fmt == sp || *fmt == 0)    {      if ( is_format != 1 || is_token != 1)      {        return -1;      }      if (value_type == 0)      {        char *pstr = va_arg(arglist,char*);        cout<<"buf1:"<<buf<<endl;        cout<<"pstr1:"<<pstr<<endl;        while(*buf != sp && *buf != 0)        {          if (*buf == '\n'||*buf == '\r')          {            buf ++;            continue;          }          cout<<"buf2:"<<buf<<endl;          cout<<"pstr2:"<<pstr<<endl;          *pstr = *buf;          buf ++;          pstr ++;        }        buf ++;        *pstr = 0;        if (*fmt == 0)          break;        is_format = is_token = 0;      }      else if (value_type == 1)      {        int *num = va_arg(arglist,int*);        *num = 0;        while(*buf != sp && *buf != 0)        {          if (*buf < '0' || *buf > '9')          {            buf ++;            continue;          }          *num = *num * 10 + *buf - '0';          buf ++;        }        buf ++;        is_format = is_token = 0;      }      else if (value_type == 2)      {        char *pch = va_arg(arglist,char*);        *pch = 0;        if (*buf != 0)        {          *pch = *buf;        }        while(*buf != sp && *buf != 0) buf ++;        buf ++;      }      is_format = is_token = 0;      if (*fmt == 0)        break;    }    else if (*fmt == 0x20)    {      fmt ++;      continue;    }    fmt ++;  }  return 0;}

三、总结

（1）文中大部分是测试代码，若需要使用可直接从文中复制测试。
（2）字符串的操作还有很多思想比较特别的，总结后可以慢慢体会。
（3）若有建议，请留言，在此先感谢！