十六進制值比較並保存到文件C++

Question

我正在讀取H.264比特流作爲C++中的Hex文件。我想在某些條件滿足時插入一些字符串。

像在附加圖像中，如果00 00 00 01的十六進制值出現在文件中的任何位置，我想在文件00 00 00 01之前添加一些像ABC這樣的字符串，並將其另存爲新文件。現在寫我的方法是以十六進制格式讀取h.264文件。將其轉換爲字符串並進行字符串比較。如果有辦法我可以做一個直接的十六進制比較？這裏是我當前的代碼

#include "stdafx.h" 
#include <iostream> 
#include <fstream> 
#include <sstream> 
#include <string> 
#include <iomanip> 
using namespace std; 

int _tmain(int argc, _TCHAR* argv[]) 
{ 
unsigned char x; 
string s1,s2,s3; 
s2="Mushahid Hussain"; 
s3="0000000141"; 
std::ifstream input("d:\\Jm\\videos\\trying2.264", std::ios::binary); 
input >> std::noskipws; 
while (input >> x) { 
    long constant = 0x0000000168; 
    std::ostringstream buffer; 

    buffer << std::hex << std::setw(2) << std::setfill('0') 
      << (int)x; 
    s1=buffer.str(); 
    if (s1.find(s1) != std::string::npos) { 
     cout<<"hello"; 
    s1+=s2; 
} 
std::ofstream outfile; 

    outfile.open("d:\\Jm\\bin\\trying5.264", std::ios_base::app); 
    outfile << s1; 

} 

    return 0; 
} 

編輯1
作爲回答Tommylee2k我能夠追加字符串。但問題是在文件末尾的十六進制CD值附加如附圖所示。

Answer 1

也許更好的方法是將二進制文件讀入內存緩衝區，然後找到memcmp（）。 當你找到你的方式，你寫的提前比賽的塊，那麼你的「ABC」 -string，並繼續搜索該文件

#include <stdio.h> 
#include <string.h> 
#include <memory.h> 
#include <malloc.h> 

char pattern[4]= { 0x00,0x00,0x01,0x67 }; 

char *memfind(char *s, int len, char *p, int plen) { 
    int n=0; 
    char *pos = s; 
    while ((pos-s)<(len-plen)) { 
     while (*(pos+n) == *(p+n) && n<=plen) n++; 
     if (n==plen) 
      return pos; 
     pos++;n=0; 
    } 
    return NULL; 
} 

int main() { 
    FILE *in = fopen("in.vid", "r+"); 
    FILE *out = fopen("out.vid", "wb"); 

    // get Filesize 
    size_t size = 0; 
    fseek(in, 0L, SEEK_END); 
    size = ftell(in); 

    // read whole file in 
    char *buffer = malloc(size); 
    fseek (in, 0L, SEEK_SET); 
    fread (buffer, size, 1, in); 

    char *currentPos = buffer; 
    char *found; 
    if (buffer) { 
     while (1) { 
      found = memfind(currentPos, size-(currentPos-buffer), pattern, sizeof(pattern)); 
      if (found==NULL) break; 
      fwrite(currentPos, 1, (size_t) (found-currentPos), out); 
      fwrite("ABC", sizeof("ABC"), 1, out); 
      fwrite(pattern, sizeof(pattern),1,out); 
      currentPos=found+4; 
     } 
     fwrite (currentPos, 1, (size_t) size - (currentPos-buffer), out); 
     free(buffer); 
    } 
    fclose (in); 
    fclose (out); 

    return 0; 
}