Question

我正在尝试为作业编写程序，但每当我运行它时，程序就会终止，并说：

terminate called after throwing an instance of 'std::out_of_range' 
what(): basic_string::substr

这是我整个程序的代码：

//Jaime Rhoda! Program 6! Sleep deprivation!
//This program will read in a list of dates.
//It will then seperate the months, days, and years.
//It will print the dates in a variety of styles.

#include <fstream>
#include <string>
using namespace std;

ifstream input ("input.txt");
ofstream output ("output.txt");
string readoriginaldate ();
void breakoriginaldate (string, string&, string&, string&);
void printdate3ways (string,string,string);
int main() {
    output<<"This is Jaime! Welcome to program 6! I'm tired :(\n\n";
    while (input) {
        string month,day,year;
        string date=readoriginaldate();
        breakoriginaldate(date, month, day, year);
        printdate3ways(month,day,year);
    }
    return 0;
}
// This function takes no parameter.
//It reads in one character string from a file.
//It returns the string. Nice and simple.
string readoriginaldate() {
    string date;
    input>>date;
    return date;
}
//This function reads in a string (date).
//It seperates the string into 3 parts.
//It returns no value.
void breakoriginaldate (string date, string &day, string &month, string &year) {
    int pos=date.find('/');
    day=date.substr(0,pos-1);
    int pos2= date.find('/',pos+1);
    month=date.substr(pos+1,pos2-pos);
    year=date.substr(pos2,2);
    output<<date<<" is the original date.\n\n";
    output<<month<<" is the month \t"<<day<<" is the day.\t"<<year<<" is the year.\t\t";     
}
//This function takes the month, day, and year.
//It prints them the American way, and all the other ways.
//It returns no value, like a bad invesment!
void printdate3ways(string month,string day,string year) {
    string wordmonth;
    if (month=="1")
        wordmonth="January";
    if (month=="2")
        wordmonth="February";
    if (month=="3")
        wordmonth="March";
    if (month=="4")
        wordmonth="April";
    if (month=="5")
        wordmonth="May";
    if (month=="6")
        wordmonth="June";
    if (month=="7")
        wordmonth="July";
    if (month=="8")
        wordmonth="August";
    if (month=="9")
        wordmonth="September";
    if (month=="10")
        wordmonth="October";
    if (month=="11")
        wordmonth="November";
    if (month=="12")
        wordmonth="December";
    string fullmonth, fullday;
    if (day.length()<2)
        fullday='0'+day;
    else
        fullday=day;
    if (month.length()<2)
        fullmonth='0'+month;
    else
        fullmonth=month;

    string european=day+'-'+month+'-'+year;
    string american=wordmonth+""+day+", "+"20"+year;
    string full=fullmonth+'-'+fullday+'-'+"20"+year;
    output<<"The European way-> "<<european<<"\n\n";
    output<<"The American way-> "<<american<<"\n\n";
    output<<"The full way-----> "<<full<<"\n\n\n";
}

Answer 1

如果输入数据不正确，可能会发生错误。由于您没有检查正确的格式，请尝试正确输入日期。您也错误地提取数据字段。

尝试以下功能定义

void breakoriginaldate ( const string &date, string &day, string &month, string &year ) 
{
   string::size_type pos = date.find( '/' );
   day = date.substr( 0, pos );
   string::size_type pos2 = date.find( '/', pos + 1 );
   month = date.substr( pos + 1, pos2 - pos - 1 );
   year = date.substr( pos2 + 1 );

   output << date << " is the original date.\n\n";
   output << month << " is the month \t"<<day << " is the day.\t" << year<<" is the year.\t\t";     
}

std :: out_of_range what（）：basic_string :: substr

1 个答案: