Operators & Control Flow

1#include <stdint.h>
2#include <stdbool.h>
3
4int main() {
5    int a = 10;
6    int b = 3;
7
8    // Arithmetic
9    int sum = a + b;
10    int diff = a - b;
11    int product = a * b;
12    int quotient = a / b;   // integer division — 10/3 = 3
13    int remainder = a % b;  // modulo — 10%3 = 1
14
15    // Comparison (returns 0 for false, 1 for true)
16    if (a == b) { /* equal */ }
17    if (a != b) { /* not equal */ }
18    if (a > b)  { /* greater than */ }
19    if (a <= b) { /* less than or equal */ }
20
21    // Logical
22    bool flag = false;
23    if (a > 0 && b > 0) { /* both true */ }
24    if (a > 0 || b > 0) { /* at least one true */ }
25    if (!flag) { /* flag is false */ }
26
27    // Bitwise (very common in embedded — setting/clearing register bits)
28    uint8_t reg = 0x00;
29    reg |= (1 << 3);    // set bit 3 (OR)
30    reg &= ~(1 << 3);   // clear bit 3 (AND NOT)
31    reg ^= (1 << 3);    // toggle bit 3 (XOR)
32    
33    if (reg & (1 << 3)) { 
34        // check if bit 3 is set 
35    }
36
37    return 0;
38}

1int sensor_value = 512;
2
3if (sensor_value > 800) {
4    printf("High\n");
5} else if (sensor_value > 200) {
6    printf("Normal\n");
7} else {
8    printf("Low\n");
9}

1typedef enum {
2    MODE_STA,
3    MODE_AP,
4    MODE_STA_AP
5} wifi_mode_t;
6
7wifi_mode_t mode = MODE_STA;
8
9switch (mode) {
10    case MODE_STA:
11        printf("Station mode\n");
12        break;
13    case MODE_AP:
14        printf("Access Point mode\n");
15        break;
16    case MODE_STA_AP:
17        printf("Combined mode\n");
18        break;
19    default:
20        printf("Unknown mode\n");
21        break;
22}

1// 1. FOR loop — used when you know the exact iteration count
2for (int i = 0; i < 10; i++) {
3    printf("i = %d\n", i);
4}
5
6// 2. WHILE loop — used when a condition determines termination
7int retries = 0;
8while (!wifi_connected() && retries < 5) {
9    retry_connect();
10    retries++;
11}
12
13// 3. INFINITE loop — the main pattern in embedded firmware
14while (1) {
15    // Super loop: read sensors, process, act
16    read_sensors();
17    process_data();
18    
19    // Always yield the CPU in an RTOS environment!
20    vTaskDelay(pdMS_TO_TICKS(100));
21}