C++ changing the char of Vector <string>

Question

void encodeUpper (vector <string> &book, int &cipher){

string word;

char asciiNum;

for(int i=0;i<book.size();i++){

if (IsUpper(book[i][i]) == true){

if (book[i][i] != ' ' ) {

asciiNum = (book[i][i]+cipher) % 91 ;

if (asciiNum<cipher){

book[i][i]+=65;

word = book[i];

}

}

}

}

}

//I'm trying to change the char of vector <string> please help

Answer 1

This is the very reason why I never jumped ship to the C++ string class. You CANNOT change a specific character inside a String object. In General, you CANNOT manipulate the string at the byte level. You have to convert it to a C-style string that is null terminated.

fortunately the method c_str() will do just that.

So I would recommend using the following function:

inline void String2CharArray( std::string & Str, char * str)

{

strcpy(str,Str.c_str());

}

Note that you will have to get the size of the string and allocate a buffer

for the C-style string. You can then do what you want with the C-style string

without changing the original std::string

Here is an example of what I am talking about:

//=========================================================

using namespace std;

#include <iostream>

#include <string>

#include <string.h>

#include <stdlib.h>

inline void String2CharArray( std::string & Str, char * str)

{

strcpy( str, Str.c_str());

}

int main()

{

string str="HE SAID HELLO";

int strLen = str.length();

char * strBuff = (char *) malloc(strLen+1); //allows for null terminator

String2CharArray( str, strBuff);

cout << str << endl; // HE SAID HELLO

cout << strBuff << endl; // HE SAID HELLO

//changes occur here.....

strBuff[0]='M';

strBuff[8]='J';

memcpy( &strBuff[3], (char*)"LIKE", 4 ); // typecast prevents the compiler warning

cout <<"-----------------------------------" << endl;

cout << str << endl; // HE SAID HELLO

cout << strBuff << endl; // ME LIKE JELLO

free(strBuff);

}

I would recommend familiarizing yourself with the functions in string.h

and stdlib.h

Otherwise you will have to hope that the great leaders of C++ will create

methods for manipulating string objects at the byte level...

I am not holding my breath, nor am I jumping ship.

I guess I'm just too old-fashioned and too old-school...

Oh well, cheers!