Question

这是我第一次访问此网站，感谢您对我的问题提供任何帮助。我在我的第一个C ++课程中，我承认我不是计算机程序设计的专家，所以如果你能尽可能地让你的答案变得愚蠢，那么这将极大地帮助我的初学者地位。

我将创建一个解码加密文本文件的程序。这些文件由几组十个整数组成。根据文件的不同，文件中每个字符的编号之前都有许多随机值。例如，在一个文件中，可能有三个随机数，而不是代表一个字符的数字，然后是三个随机数，而不是代表一个字符的下一个数字，依此类推。

程序将需要提示用户输入文件，然后输出文件，以及在每个合法整数/字符之前跳过的随机数。请注意，我的程序需要能够处理任意数量的前导随机数。这意味着它可能在合法的数字之前有三个随机数，或之前有三十个随机数。

到目前为止，这是我的整个计划。我需要创建的函数叫做skipVariable，如果有人可以帮我创建这个函数，那将是非常有用的，我已经盯着它好几个小时了，我无法想象如何完成这个任务。

//Header Files
#include <iostream> 
#include <fstream> 

using namespace std;

// Global Constants

const char SPACE = ' ';

//Function Prototypes


/*
name: programTitle
input: none
output: void (string)
dependencies: none
process: output string
*/
void programTitle();

/*
name: promptUser
input: none
output: void file name and int skip number
dependencies: none
process: output string name and skip number int
*/
void promptUser ( string &IN_FILE_NAME, string &OUT_FILE_NAME, int &SKIP_NUMBER);

/*
name: openInputFile
input: ifstream &inf, &fileName (string)
output: good bad file (bool)
dependencies: none
process: test if file can be opened/ does it exist
*/
bool openInputFile( ifstream &inf, const string &fileName );

/*
name: skipVariable
input: skip number(integer)
output: calculated result (int)
dependencies: none
process: ( skip variable in file and give exstracted number)
*/
int skipVariable (int SKIP_NUMBER);

// Main function/program
int main ()
{
// initalize function/variables

ifstream fin;
string IN_FILE_NAME, OUT_FILE_NAME;
int SKIP_NUMBER;

//Print Program Title
//Function Name: programTitle
programTitle();

//Prompt user for input file name and skip number
//Function Name: promptUser
promptUser ( IN_FILE_NAME, OUT_FILE_NAME, SKIP_NUMBER);

//Check it file is usable and openable
//Function Name: openInputFile
openInputFile( fin, IN_FILE_NAME);

//Skip variable number
//Function Name: skipVariable
skipVariable ( SKIP_NUMBER);




//Close input file
fin.close();

// make spaces before program end   
cout << endl << endl;

// End program
system( "pause" );

return 0;
 }

// Supporting function implementation
//

 //Display Program Title
void programTitle()
 {

  // output prompt string
cout << "     DECODER PROGRAM" << endl;
cout << "     ===============";
cout << endl << endl;

 // void function - no return
}


 //Prompt user for Input
void promptUser ( string &IN_FILE_NAME, string &OUT_FILE_NAME, int &SKIP_NUMBER)
{
//prompt for an input file name
cout << "Enter input file name: " ;
        cin >> IN_FILE_NAME;
cout << endl;

//Prompt for an output file name
cout << "Enter output file name: " ;
        cin >> OUT_FILE_NAME;
cout << endl;  

//Prompt for number of items to skip
cout << "Enter number of items to skip: " ;
        cin >> SKIP_NUMBER;
cout << endl << endl << endl;

// Print process data indication
cout << "Processing Data . . ." << endl << endl;

//void function no return
}


//Function opens file and checks if file exists
bool openInputFile( ifstream &inf, const string &fileName )
{
// clear and open input file
inf.clear();
inf.open( fileName.c_str() );

// return input file condition
return inf.good();

}


//Functio skips variables and returns needed integer
int skipVariable (int SKIP_NUMBER)

//Is the file good/usable
 {

//start loop skip valued variable

       //get number representing character

       //output as file character

// return values
return 0; //temporary return
}

Answer 1

跳过读取文件的函数需要一个文件流句柄。

int skipVariable (ifstream const& in, int SKIP_NUMBER) {
   int r[ 3 ]; /* store the random numbers */
   char c;
   int nchars = 0; /* number of characters read sucessfully from the file */
   while (in >> r[ 0 ] >> r[ 1 ] >> r[ 2 ]) { 
       in >> c; /* read a character */
       ++nchars;
       cout << c; /* emit to console for testing */
   }
   nchars;
 }

Answer 2

您可能需要在循环中调用skipNumber(），并为其提供一个额外的参数ifstream，正如他在答案中所表达的那样。

伪代码（这进入你的main（）函数）：

const numbersToSkip = 3;
string result = "";
loop until end of file is reached
    char c = skipVariabble(ifstream, numbersToSkip);
    result += c;
end of loop

skipVariable（）看起来像这样：

numberCounter = 0;
while not at end of file
    read single number
    numberCounter += 1
    if(numberVounter modulo 4 equals 0)
        return number;
end of loop

return SPACE; // if we get here, the file end is reached

创建一个C ++程序来跳过文本文件中的整数？

2 个答案: