Read File Char by Char C++ Get Random Values

random character generate

im writing a program to aid me empathize on rand fucntion i dont get how to utilize it with a file that has a bunch of characters i recollect i would accept to do it in a loop so information technology could exist random and set srand (fourth dimension(Naught));

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#include <iostream> #include <stdlib.h> #include <time.h> #include <fstream> #include <string.h> #include <cstdlib> using namespace std; struct characters { char setOfCharacter; }; int main() { characters charInfo[iv]; ifstream inFile; inFile.open("grapheme.txt"); while(!inFile) { cout << "error" << endl; return 0; } for(int i =0; i<4; i++) { inFile >> charInfo[i].setOfCharacter; } inFile.close(); return 0; }

hither is my file
4
ABC
Abc
AbC
aBC

i got it random generate but i want to take hold of a just one line not all the lines

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#include <iostream> #include <stdlib.h> #include <time.h> #include <fstream> #include <string.h> #include <cstdlib> using namespace std; struct characters { char setOfCharacter1; char setOfCharacter2; char setofCharacter3; }; int main() { int totalCharacter=four; characters charInfo[totalCharacter]; srand(time(NULL)); ifstream inFile; inFile.open("character.txt"); while(!inFile) { cout << "mistake" << endl; return 0; } for(int i =0; i<totalCharacter; i++) { inFile >> charInfo[i].setOfCharacter1; inFile >> charInfo[i].setOfCharacter2; inFile >> charInfo[i].setofCharacter3; } inFile.close(); for(int i =0; i<totalCharacter; i++) { int x =rand() %4; cout << charInfo[10].setOfCharacter1 << charInfo[x].setOfCharacter2 << charInfo[x].setofCharacter3 <<endl; }

Last edited on

empathise on rand fucntion

past all means practise so but the most upward-to-engagement way of generating random numbers in C++ is using the <random> library - search this forum for several examples final few weeks

use std::getline() to read the file by line into std::string, salve the lines in a std::vector<std::string>, std::random_shuffle the vector and pick-off any particular element similar vec[0], etc

i dont empathize what you mean

"use std::getline() to read the file by line into std::string, save the lines in a std::vector<std::cord>, std::random_shuffle the vector and pick-off any particular chemical element like vec[0], etc "

i want to employ rand() not the library
the things is i have character not numbers

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std::string random_line_from( std::string file_name ) { std::string selected_line ; // the randomly chosen line std::ifstream file(file_name) ; // open the file for reading std::string current_line ; // the electric current line read from the file std::size_t line_number = one ; while( std::getline( file, current_line ) ) // for each line in the file { // the current line becomes the selected line with a probability of 1 / line_number // the showtime line is selected with a probability of one // the second line replaces the selected line with a probability of ane/2 // and so now, each line so far being the selected line has a probability of 1/ii // the tertiary line replaces the selected line with a probability of 1/3 // so now, each of the three lines so far being the selected line has a probability of 1/3 // etc. if( ( std::rand() % line_number ) == 0 ) selected_line = current_line ; ++line_number ; } render selected_line ; }

http://coliru.stacked-kleptomaniacal.com/a/8d76660426f8b27e

i have graphic symbol not numbers

who said anything about numbers?

why when it'due south not the most accurate option bachelor unless your professor insists

i just want to exist able to but to employ rand() srand(time(nothing))

cheers for the case @jlborgers
since it a cord could i practise it with a character

Concluding edited on

If C-fashion arrays must be used:

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// assumes that no line in the file is longer than 4095 characters const std::size_t MAX_LINE_SZ = 4096 ; // +1 for the zero-graphic symbol at the terminate char* random_line_from( const char* file_name, char selected_line[MAX_LINE_SZ] ) { selected_line[0] = 0 ; // initialise to a zilch string std::ifstream file(file_name) ; // open up the file for reading char current_line[MAX_LINE_SZ] ; // the electric current line read from the file std::size_t line_number = 1 ; while( file.getline( current_line, MAX_LINE_SZ ) ) // for each line in the file { // the current line becomes the selected line with a probability of one / line_number // the first line is selected with a probability of 1 // the 2nd line replaces the selected line with a probability of ane/2 // so now, each line so far being the selected line has a probability of 1/two // the 3rd line replaces the selected line with a probability of 1/3 // so now, each of the 3 lines and so far existence the selected line has a probability of 1/3 // etc. if( ( std::rand() % line_number ) == 0 ) std::strcpy( selected_line, current_line ) ; ++line_number ; } return selected_line ; }

http://coliru.stacked-crooked.com/a/4574c133474cd9bc

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Source: https://www.cplusplus.com/forum/general/210722/

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