Datasheet

fprintf(filePtr,"Writing out some important data...%d, %d, %d\n",2,3,4);
fclose(filePtr); /* Close textFile.txt, flushing data to disk */
,
#include <std io.h>
int main(int argc, char *argv[]) {
int mask = 163; /* Declare an int and assign it with a value less than 256. * /
char c; /* Declare a character (which is one byte, maximum value 255.) */
FILE *inputFi le = 0, *outputFile = 0; /* declare two file pointers */
if(argc!=3) { /* Check the number of arguments */
printf(" Usag e: %s <input file> <output file>\n",argv[0]);
return 1; /* Report an error */
}
inputFile = fopen(argv[1],"r"); /* Open the input file. */
if(!inputFile) return 2; /* If file pointer is null return an error. */
outputFile = fopen(argv[2],"w"); /* Open the output file. */
if(!outputFile) return 3; /* If the file pointer is null return an error */
c = fgetc(inputFile); /* Get the first character. */
while(c != EOF) { /* Loop until end-of-file is reached. */
c ^= mask; /* Exclusive-OR with the mask. */
fputc(c,outputFile); /* Write to the output file. */
c = fgetc(inputFile); /* Get another character. */
}
fclose(inputFile); /* Close the input fil e. */
fclose(outputFile); /* Close the output f ile. */
return 0; /* Return success to the operating system */
}
, 2 ^ 3 = 1 10 ^ 11 = 01
#include <std lib.h>
int newMask() {
int mask = (double)rand()/RAND_MAX*254+1; /* Number between 1 and 255 */
return mask;
}
int main(){
srand(1234567); /* Set the seed once */
int mask = newMask(); /* Get a new mask each time it is used. */
return 0;
}