In the Stack Overflow podcasts, Joel Spolsky constantly harps on Jeff Atwood about Jeff not knowing how to write code in C. His statement is that \"knowing C helps you write bet
For the purposes of argument, suppose you wanted to concatenate the string representations of all the integers from 1 to n (e.g. n = 5 would produce the string "12345"). Here's how one might do that naïvely in, say, Java.
String result = "";
for (int i = 1; i <= n; i++) {
result = result + Integer.toString(i);
}
If you were to rewrite that code segment (which is quite good-looking in Java) in C as literally as possible, you would get something to make most C programmers cringe in fear:
char *result = malloc(1);
*result = '\0';
for (int i = 1; i <= n; i++) {
char *intStr = malloc(11);
itoa(i, intStr, 10);
char *tempStr = malloc(/* some large size */);
strcpy(tempStr, result);
strcat(tempStr, intStr);
free(result);
free(intStr);
result = tempStr;
}
Because strings in Java are immutable, Integer.toString
creates a dummy string and string concatenation creates a new string instance instead of altering the old one. That's not easy to see from just looking at the Java code. Knowing how said code translates into C is one way of learning exactly how inefficient said code is.