The do...while loop works in the same manner as the while loop, with the exception that the condition is tested at the end of the loop, so the do loop will always run at least once.
do {
// statement block
} while (condition);
condition: a boolean expression that evaluates to true or false.
// initialize x and i with a value of 0
int x = 0;
int i = 0;
do {
delay(50); // wait for sensors to stabilize
x = readSensors(); // check the sensors
i++; // increase i by 1
} while (i < 100); // repeat 100 times