问题描述
所以我在做一个项目,我需要检查某个文件是否包含另一个文件的内容。
我在 c 中创建了一个函数(它是 c 不是 c++)来尝试它,但它似乎进入了一个无限循环并且总体上不起作用,我尝试使用 Visual Studio 调试器,但它没有给我更多信息。
注意:我包括 stdlib.h
代码:
int findFileInFile(const char* wherePath,const char* whatPath)
{
FILE* fpBigger = fopen(wherePath,"r");
FILE* fpSmaller = fopen(whatPath,"r");
if (fpBigger != NULL && fpSmaller != NULL)
{
unsigned char cs = 0;
unsigned char cb = 0;
while ((cb = fgetc(fpBigger)) != EOF)
{
cs = fgetc(fpSmaller);
if (cs == EOF)
return 1;
if (cs != cb)
{
fseek(fpSmaller,0L,SEEK_SET);
}
}
return 0;
}
else
{
printf("File names are wrong!\n");
exit(-1);
}
}
谢谢。
解决方法
我猜这就是你要找的:
#include <stdio.h>
#include <stdlib.h>
int findFileInFile(const char *wherePath,const char *whatPath)
{
FILE *fpBigger = fopen(wherePath,"rb");
FILE *fpSmaller = fopen(whatPath,"rb");
if (fpBigger != NULL && fpSmaller != NULL)
{
unsigned char cs = 0;
unsigned char cb = 0;
int s;
int b;
while (1)
{
b = fgetc(fpBigger);
s = fgetc(fpSmaller);
if (s == EOF && b == EOF) //if both return values from fgetc are EOF,it means you've reached the end of the file which wouldn't have been possible if both of the files weren't equal
{
return 1;
}
else if (s == EOF || b == EOF)
{
return 0;
}
cs=(unsigned char)s; //casting the int to unsigned char
cb=(unsigned char)b; //casting the int to unsigned char
if (cs != cb) //compare the characters gotten from the files,if not equal,return 0
{
return 0;
}
}
}
else
{
printf("File names are wrong!\n");
exit(-1);
}
}
int main()
{
printf("%d",findFileInFile("file1.txt","file2.txt"));
}
最后但并非最不重要的一点,您还可以使用 feof()
检查是否已到达文件流的末尾。
编辑:(这可能不是最佳解决方案,但它会检查较大的文件是否包含较小的文件)
#include <stdio.h>
#include <stdlib.h>
int findFileInFile(const char *wherePath,"rb");
unsigned char cs = 0;
unsigned char cb = 0;
int s;
int b;
int loc;
if (fpBigger != NULL && fpSmaller != NULL)
{
s = fgetc(fpSmaller);
cs=(unsigned char)s;
while((b=fgetc(fpBigger))!=EOF){ //checks for the first instance of the first character of the smaller file in the bigger file
cb=(unsigned char)b;
if(cs==cb){
loc=ftell(fpBigger)-1; //set loc to the position where the first character of the smaller file is found in the bigger file
break;
}
}
if(b==EOF){ //if the character is not found,return 0
return 0;
}
fseek(fpBigger,loc,SEEK_SET);
rewind(fpSmaller);
while((b=fgetc(fpBigger))!=EOF){
if((s=fgetc(fpSmaller))==EOF){ //check if the end of smaller file is reached,and return 1 if true
return 1;
}
cs=(unsigned char)s;
cb=(unsigned char)b;
if(cs!=cb){
rewind(fpSmaller); //if the characters gotten from both the files are not equal,go to the very beginning of smaller file
loc++; //increase the position to start the search from in the bigger file by 1
fseek(fpBigger,SEEK_SET);
}
}
if(b==EOF&&fgetc(fpSmaller)==EOF){
return 1;
}
return 0;
}
else
{
printf("File names are wrong!\n");
exit(-1);
}
}
int main()
{
printf("%d","file2.txt"));
}