I am trying to print in reverse all characters in a file. I want to use fseek to do so. Here are my codes..but can't get it to work!!!
Code:#include <stdio.h> #include <stdlib.h> int main(void) { FILE *ifp; int k; if((ifp=fopen("hello.txt","rb"))==NULL) { perror("fseek1"); exit(1); } fseek(ifp,0L,SEEK_END); for (k=0;k<sizeof(ifp);k++) printf("%c",ifp); close(ifp); return 0; }
In your code, the file-pointer doesn't change. You could try to replace the filepointer. Perhaps something like
ifp = ifp - 1;
Or you could use fseek to replace:
fseek (ifp, i, SEEK_END);
*Youch* That is definitely NOT valid. You can't change the file pointers value (address) thinking it would reposition the position in the file. The file pointer points to a place in memory where the file data is stored, it doesn't point to the file itself.ifp = ifp - 1;
I don't know if there is any good/easy way to traverse a file backwards, but you could try this:
Code:FILE* File; ... fseek(File, 0, SEEK_END); int Position = ftell(File); while(Position >= 0) { fseek(File, Position, SEEK_SET) // Read data using fread(); Position--; } ...
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>>printf("%c",ifp);
That won't work either, I'm afraid. It will not get a character from ifp and print it out.
Lookup fgetc(), but it won't be very efficient, you'll spend most of your time repositioning the file pointer.
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If you're posting code, use code tags: [code] /* insert code here */ [/code]
Code:void revers(FILE *f){ int n=0; if((f=fopen("f.dat","r"))==NULL) printf("sorry no memory\n"); else{ fseek(f,0,SEEK_END); n=ftell(f)/size//the size of file // n count of file for(i=1;i<=n;i++) fsee;(f,-pos(i-1),SEEK_END); fread(-------------------- printf(------------------ } fclose(f); }
What was the point of bumping a year old thread?
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