Chapter 69: Iteration

Section 69.1: break

Jumps out of the nearest enclosing loop or switch statement.

// print the numbers to a file, one per line for (const int num : num_list) {

errno = 0;

fprintf(file, "%d\n", num); if (errno == ENOSPC) {

fprintf(stderr, "no space left on device; output will be truncated\n"); break;

}

}

Section 69.2: continue

Jumps to the end of the smallest enclosing loop.

int sum = 0;

for (int i = 0; i < N; i++) { int x;

std::cin >> x;

if (x < 0) continue; sum += x;

// equivalent to: if (x >= 0) sum += x;

}

Section 69.3: do

Introduces a do-while loop.

// Gets the next non-whitespace character from standard input char read_char() {

char c; do {

c = getchar();

} while (isspace(c)); return c;

}

Section 69.4: while

Introduces a while loop.

int i = 0;

// print 10 asterisks while (i < 10) {

putchar('*'); i++;

}

Section 69.5: range-based for loop

std::vector<int> primes = {2, 3, 5, 7, 11, 13};

for(auto prime : primes) { std::cout << prime << std::endl;

}

Section 69.6: for

Introduces a for loop or, in C++11 and later, a range-based for loop.

// print 10 asterisks

for (int i = 0; i < 10; i++) { putchar('*');

}