带有printf的C++奇怪输出
C++ weird output with printf
下面是我的函数，它假设列出一些国家我尝试使用<lt；已修复，但似乎对没有帮助
这是我的输出：
�ѿra
�ѿd Arab Emirates
�ѿnistan
�ѿua and Barbuda
�ѿlla
�ѿia
�ѿia
�ѿrlands Antilles
�ѿa
�ѿctica
�ѿtina
�ѿcan Samoa
我的文本文件还可以，我想知道我的数据转换是否有错误。
这是我的CountryData.cpp文件
#include <iostream>
#include <string.h>
#include "CountryData.h"
using namespace std;
// ====================================================================
void readData ()
{
FILE * pFile;
NoOfRecordsRead = 0;
char buffer [Line_Char_Buffer_Size];
pFile = fopen (INPUT_FILE_NAME , "r");
if (pFile == NULL)
perror ("Error opening file 'Countries.txt' !");
else
{
while ( !feof (pFile) )
{
char* aLine = get_line (buffer, Line_Char_Buffer_Size, pFile);
if (aLine != NULL)
{
// printf ("%d] aLine => %sn", NoOfRecordsRead, aLine);
globalCountryDataArray [NoOfRecordsRead++] = createCountryRecord (aLine);
}
}
fclose (pFile);
}
}
// ====================================================================
char* get_line (char *s, size_t n, FILE *f)
{
char *p = fgets (s, n, f);
if (p != NULL)
{
size_t last = strlen (s) - 1;
if (s[last] == 'n')
s[last] = ' ';
}
return p;
}
// ====================================================================
CountryRecordType createCountryRecord (char* aLine)
{
CountryRecordType ctryRec;
char* pch = strtok (aLine, LINE_DATA_DELIMITER);
// 1) Retrieve TLD
strcpy (ctryRec.TLD, pch);
pch = strtok (NULL, LINE_DATA_DELIMITER);
// 2) Retrieve Country
strcpy (ctryRec.Country, pch);
pch = strtok (NULL, LINE_DATA_DELIMITER);
// 3) Retrieve FIPS104
strcpy (ctryRec.FIPS104, pch);
pch = strtok (NULL, LINE_DATA_DELIMITER);
// 4) Retrieve ISO2
strcpy (ctryRec.ISO2, pch);
pch = strtok (NULL, LINE_DATA_DELIMITER);
// 5) Retrieve ISO3
strcpy (ctryRec.ISO3, pch);
pch = strtok (NULL, LINE_DATA_DELIMITER);
// 6) Retrieve ISONo
ctryRec.ISONo = atof (pch);
pch = strtok (NULL, LINE_DATA_DELIMITER);
// 7) Retrieve Capital
strcpy (ctryRec.Capital, pch);
pch = strtok (NULL, LINE_DATA_DELIMITER);
// 8) Retrieve Region
strcpy (ctryRec.Region, pch);
pch = strtok (NULL, LINE_DATA_DELIMITER);
// 9) Retrieve Currency
strcpy (ctryRec.Currency, pch);
pch = strtok (NULL, LINE_DATA_DELIMITER);
// 10) Retrieve CurrencyCode
strcpy (ctryRec.CurrencyCode, pch);
pch = strtok (NULL, LINE_DATA_DELIMITER);
// 11) Retrieve Population
ctryRec.Population = atof (pch);
return (ctryRec);
}
// ====================================================================
char* displayRecordContent (CountryRecordType ctryRec)
{
char * output = ctryRec.Country;
return output;
}
// ====================================================================
void showAllRecords ()
{
int i=0;
string stroutput;
char * result;
for (i=0; i<NoOfRecordsRead; i++)
{
result = displayRecordContent (globalCountryDataArray [i]);
stroutput += result;
stroutput += "n";
}
cout << fixed << stroutput << endl;
}
// ====================================================================
int findCountryRecord (const char* countryName)
{
int idx = -1;
int found = 0;
while (!found && (++idx < Max_Record_Size))
if (strcmp (globalCountryDataArray [idx].Country, countryName) == 0)
found = 1;
if (found)
return (idx);
else
return (-1);
}
// ====================================================================
char* getCapital (const char* countryName)
{
int idx = findCountryRecord (countryName);
if (idx < 0)
{
printf ("Country '%s' not found!n", countryName);
return (NULL);
}
else
return (globalCountryDataArray [idx].Capital);
}
// ====================================================================
char* getCurrencyCode (const char* countryName)
{
int idx = findCountryRecord (countryName);
if (idx < 0)
{
printf ("Country '%s' not found!n", countryName);
return (NULL);
}
else
return (globalCountryDataArray [idx].CurrencyCode);
}
// ====================================================================
main ()
{
readData ();
showAllRecords ();
}
这是我的CountryData.h文件
#ifndef COUNTRY_DATA_H
#define COUNTRY_DATA_H
// ====================================================================
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
using namespace std;
// ====================================================================
#define TLD_LEN 2
#define COUNTRY_LEN 100
#define FIPS104_LEN 2
#define ISO2_LEN 2
#define ISO3_LEN 3
#define CAPITAL_LEN 100
#define REGION_LEN 100
#define CURRENCY_LEN 50
#define CURRENCY_CODE_LEN 3
#define No_Of_Rec_Fields 11
#define Max_Record_Size 250
#define Line_Char_Buffer_Size 400
#define LINE_DATA_DELIMITER ","
#define INPUT_FILE_NAME "Countries.txt"
// ====================================================================
//const char* LINE_DATA_DELIMITER = ",";
//const char* INPUT_FILE_NAME = "Countries.txt";
typedef struct CountryRecord
{
char TLD [TLD_LEN+1]; // Top Level Domain code
char Country [COUNTRY_LEN+1];
char FIPS104 [FIPS104_LEN+1]; // Ctry code according to FIPS104 standard
char ISO2 [ISO2_LEN+1]; // Ctry code according to ISO2 standard
char ISO3 [ISO3_LEN+1]; // Ctry code according to ISO3 standard
double ISONo;
char Capital [CAPITAL_LEN+1];
char Region [REGION_LEN+1]; // E.g. Asia, Europe, etc.
char Currency [CURRENCY_LEN+1]; // Full name of currency
char CurrencyCode [CURRENCY_CODE_LEN+1]; // Currency abbreviation
double Population;
} CountryRecordType;
int NoOfRecordsRead;
CountryRecordType globalCountryDataArray [Max_Record_Size];
// ====================================================================
void readData ();
char* get_line (char *s, size_t n, FILE *f);
CountryRecordType createCountryRecord (char* aLine);
char* displayRecordContent (CountryRecordType ctryRec);
void showAllRecords ();
int findCountryRecord (const char* countryName);
char* getCapital (const char* countryName);
char* getCurrencyCode (const char* countryName);
// ====================================================================
#endif // COUNTRY_DATA_H
这是我的countries.txt文件的一部分
AD,Andorra,AN,AD,AND,20.00,Andorra la Vella,Europe,Euro,EUR,67627.00
AE,United Arab Emirates,AE,AE,ARE,784.00,Abu Dhabi,Middle East,UAE Dirham,AED,2407460.00
AF,Afghanistan,AF,AF,AFG,4.00,Kabul,Asia,Afghani,AFA,26813057.00
AG,Antigua and Barbuda,AC,AG,ATG,28.00,Saint John's,Central America and the Caribbean,East Caribbean Dollar,XCD,66970.00
AI,Anguilla,AV,AI,AIA,660.00,The Valley,Central America and the Caribbean,East Caribbean Dollar,XCD,12132.00
AL,Albania,AL,AL,ALB,8.00,Tirana,Europe,Lek,ALL,3510484.00
AM,Armenia,AM,AM,ARM,51.00,Yerevan,Commonwealth of Independent States,Armenian Dram,AMD,3336100.00
AN,Netherlands Antilles,NT,AN,ANT,530.00,Willemstad,Central America and the Caribbean,Netherlands Antillean guilder,ANG,212226.00
AO,Angola,AO,AO,AGO,24.00,Luanda,Africa,Kwanza,AOA,10366031.00
AQ,Antarctica,AY,AQ,ATA,10.00,--,Antarctic Region, , ,0.00
AR,Argentina,AR,AR,ARG,32.00,Buenos Aires,South America,Argentine Peso,ARS,37384816.00
AS,American Samoa,AQ,AS,ASM,16.00,Pago Pago,Oceania,US Dollar,USD,67084.00
AT,Austria,AU,AT,AUT,40.00,Vienna,Europe,Euro,EUR,8150835.00
AU,Australia,AS,AU,AUS,36.00,Canberra,Oceania,Australian dollar,AUD,19357594.00
由于按值将CountryRecordType传递给displayRecordContent，因此返回的指针无效，使用它会导致未定义的行为。这是因为您将返回一个指针，指向在函数调用期间生成的副本所包含的内容，当函数返回时，该副本将被销毁。
修改displayRecordContent函数，改为使用pass-by-reference。
const char* displayRecordContent (const CountryRecordType &ctryRec)
{
const char * output = ctryRec.Country;
return output;
}
我会从头开始重写代码，尝试实际使用C++而不是混合了一些C++的C。
#include <vector>
#include <string>
#include <iostream>
#include <iterator>
#include <fstream>
struct CountryRecord {
std::string TLD;
std::string Country;
std::string FIPS104;
std::string ISO2;
std::string ISO3;
double ISONo;
std::string Capital;
std::string Region;
std::string Currency;
std::string CurrencyCode;
double Population;
};
template <class T>
std::istream &get_field(std::istream &is, T &field) {
is >> field;
is.ignore(1);
return is;
}
template<>
std::istream &get_field<std::string>(std::istream &is, std::string &field) {
return std::getline(is, field, ',');
}
std::istream &operator>>(std::istream &is, CountryRecord &r) {
get_field(is, r.TLD);
get_field(is, r.Country);
get_field(is, r.FIPS104);
get_field(is, r.ISO2);
get_field(is, r.ISO3);
get_field(is, r.ISONo);
get_field(is, r.Capital);
get_field(is, r.Region);
get_field(is, r.Currency);
get_field(is, r.CurrencyCode);
return get_field(is, r.Population);
}
std::ostream &operator<<(std::ostream &os, CountryRecord const &r) {
return os << r.Country;
}
int main() {
std::ifstream in("countries.txt");
std::vector<CountryRecord> countries(
(std::istream_iterator<CountryRecord>(in)),
std::istream_iterator<CountryRecord>());
std::copy(countries.begin(), countries.end(),
std::ostream_iterator<CountryRecord>(std::cout, "n"));
return 0;
}
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