Question

From K&R C

A.6.5 Arithmetic Conversions
Many operators cause conversions and yield result types in a similar way. The effect is to bring
operands into a common type, which is also the type of the result. This pattern is called the
usual arithmetic conversions.

In the code below EOF is defined to be -1 which is a signed integral constant, ch should then be converted to int and while loop should be exited eventually, but doesn’t seem to happen ! Hence the Qn.

int main()
{
 unsigned char ch;
 FILE* fp;
 fp = fopen("myfile.txt","r");
 while((ch=getc(fp)) != EOF)
 {
  printf("%c", ch);
 }
 fclose(fp);
 return 0;
}

Answer 1

getc returns an int (as it must be able to hold all character values as well as EOF).

In your code, you truncate this value to unsigned char when you assign it to ch. Then you extend it to int, which will never result in EOF, as -1 truncated becomes 255, which will become the int 255.