獲取文件大小，文件擴展名和下C/C++

Question

我在寫我自己的日誌上換用C/C++槽DEV C++

它應該改變一個不同的名稱，它分配給新的文件夾在登錄屏幕背景上的圖像，但我希望它從用戶輸入中獲取圖像，檢查它是否在245KB以下，並且它是否是* .jpeg文件。

理想情況下，它將在set_image（）函數中完成。 這裏是我當前的代碼，如果它的任何幫助你：

#include<stdio.h> 
#include<windows.h> 
#include<conio.c> 
#include<stdlib.h> 

int patch(){ 
    system("cls"); 
    system("regedit /s ./src/patch.reg"); 
    system("md %windir%/system/oobe/info/backgrounds"); 
    gotoxy(12,35); 
    printf("Patch Successful!"); 
    return 0; 
} 

int unpatch(){ 
    system("regedit /s ./src/unpatch.reg"); 
    system("rd /q %windir%/system/oobe/info/backgrounds"); 
    gotoxy(12,35); 
    printf("Unpatch Successful!"); 
    return 0; 
} 

int set_image(){ 


} 


main(){ 
     int i; 
     system("cls"); 
     gotoxy(10,1); 
     printf("LOGON CHANGER V0.1"); 
     gotoxy(30,10); 
     printf("1 - Patch"); 
     gotoxy(30,11); 
     printf("2 - Unpatch"); 
     gotoxy(30,12); 
     printf("3 - Set Image"); 
     gotoxy(15,25); 
     printf("Insert your option"); 
     gotoxy(35,25); 
     scanf("%i",&i); 
     switch(i){ 
       case 1: 
         patch(); 
         break; 
       case 2: 
         unpatch(); 
         break; 
       case 3: 
         set_image(); 
         break; 
       default: 
         system("cls"); 
         gotoxy(35,12); 
         printf("Not a valid input, try again ;)"); 
         Sleep(3000); 
         main(); 
     } 
} 

Answer 1

您可以在C標準庫類和公用事業屈指可數做到這一點++。下面的例子應該讓你開始。您需要更改錯誤處理並進行修改以滿足您的特定需求。

#include <algorithm> 
#include <fstream> 
#include <string> 
#include <cctype> 

bool set_image(
    const std::string& inPathname, 
    const std::string& outPathname, 
    size_t maxSize) 
{ 
    // Validate file extension 
    size_t pos = inPathname.rfind('.'); 
    if (pos == std::string::npos) 
    { 
     return false; 
    } 

    // Get the file extension, convert to lowercase and make sure it's jpg 
    std::string ext = inPathname.substr(pos); 
    std::transform(ext.begin(), ext.end(), ext.begin(), std::tolower); 
    if (ext != ".jpg") 
    { 
     return false; 
    } 

    // open input file 
    std::ifstream in(inPathname, std::ios::binary); 
    if (!in.is_open()) 
    { 
     return false; 
    } 

    // check length 
    in.seekg(0, std::ios::end); 
    if (in.tellg() > maxSize) 
    { 
     return false; 
    } 
    in.seekg(0, std::ios::beg); 

    // open output file 
    std::ofstream out(outPathname, std::ios::binary); 
    if (!out.is_open()) 
    { 
     return false; 
    } 

    // copy file 
    std::copy(
     std::istream_iterator<char>(in), 
     std::istream_iterator<char>(), 
     std::ostream_iterator<char>(out)); 

    return true; 
}