I have the following code snippet that reads line by line from a text file, end to beginning of string . How do I change it, so that this action occurs in reverse?
while (getline (entrada, linha)){
int tam_linha = linha.size(); /* Tamaho da linha, caracateres por linha */
for(int i=tam_linha-1; i>=0; i--)
{
if(linha[i] == ' ' && linha[i-1] == linha[i])
{
linha.erase(linha.begin()+i);
}
}
}
If the intention is to read line by line of a text file by filtering the contents of each line with the removal of double spaces by single spaces, follow 2 C ++ solutions using STL :
Using the functions std::unique() and std::string::erase() :
#include <iostream>
#include <fstream>
#include <string>
#include <algorithm>
using namespace std;
bool check_double_spaces( char a, char b) { return ((a == b) && (a == ' ')); }
int main()
{
string linha;
ifstream entrada("arquivo.txt");
while( getline( entrada, linha) )
{
string::iterator end = unique( linha.begin(), linha.end(), check_double_spaces );
linha.erase( end, linha.end() );
cout << linha << endl;
}
return 0;
}
Using the functions std::string::find() and std::string::replace() :
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main()
{
string linha;
ifstream entrada("arquivo.txt");
size_t idx;
while( getline( entrada, linha ) )
{
while( (idx = linha.find(" ")) != string::npos ) // Dois espaços
linha.replace( idx, 2, " " ); // Um espaço
cout << linha << endl;
}
return 0;
}
int main(void) {
FILE *ficheiro = fopen("arquivo.txt", "r");
if(ficheiro == NULL){
printf("\nErro");
exit(1);
}
char linha[100];
while(fgets(linha, 100, ficheiro){ //essa função vai ler todo o ficheiro
printf("\n%s", linha);
}
}
Another solution (if I understood correctly) would be to use regular expressions:
#include <string>
#include <iostream>
#include <regex>
using namespace std;
int main()
{
regex reg("[ ]+");
string linha;
while (getline(cin, linha))
cout << regex_replace(linha, reg, " ") << "\n\n";
return 0;
}
All multiple spaces will be replaced by only one.