- #include <math.h>
- // define range of temperature measurement
- #define MIN_TEMP -20
- #define MAX_TEMP 80
- // define voltage and resistor values
- #define VREF 5 // reference voltage
- #define R25 10000 // resistance [url=home.php?mod=space&uid=72445]@[/url] 25degC
- /* measure the resistance of the thermistor */
- int measure_resistance(void){
- ...
- }
- /* Calculate temperature from resistance value */
- float calculate_temperature(int resistance) {
- double temp;
- temp = log(resistance/R25); // natural logarithm
- temp = 1 / (0.001129148 + (0.000234125 + (0.0000000876741 * temp * temp )) * temp ); // Steinhart-Hart equation
- temp = temp - 273.15; // Convert Kelvin to Celsius
- temp = (temp * 9.0)/ 5.0 + 32.0; // Convert to Fahrenheit
- if (temp<MIN_TEMP || temp > MAX_TEMP ) {
- // invalid temperature, handle error
- }
- return temp;
- }
- /* main function */
- int main( void ) {
- int resistance;
- float temperature;
-
- resistance = measure_resistance();
- temperature = calculate_temperature(resistance);
- printf("The temperature is: %.1f °F", temperature);
- return 0;
- }
| 
楼主
，并且浮点数还不加f
