如何把float转换成char

magnet999999

我用的TM1650LED数字模块，不能把计算出的数据直接显示，需要按照下面的格式才能行TM1650 displayString(char *aString);
但是计算出的数据是float类型的，我该怎么转换。
原程序如下
int dustPin=A0;
int dustVal=0;

int ledPower=2;
int delayTime=280;
int delayTime2=40;
float offTime=9680;
void setup(){
Serial.begin(9600);
pinMode(ledPower,OUTPUT);
//pinMode(4, OUTPUT);
}

void loop(){
// ledPower is any digital pin on the arduino connected to Pin 3 on the sensor
digitalWrite(ledPower,LOW); // power on the LED
delayMicroseconds(delayTime);
dustVal=analogRead(dustPin); // read the dust value via pin 5 on the sensor
delayMicroseconds(delayTime2);
digitalWrite(ledPower,HIGH); // turn the LED off
delayMicroseconds(offTime);

delay(3000);
Serial.println(dustVal);


float dustVal2=dustVal;
dustVal2=(dustVal2*5/1024-0.0356)*120000;
Serial.println(dustVal2);//实际的颗粒数

if(dustVal2<76)
{
Serial.println("EXCELLENT");
}
else if(dustVal2<151)
{
Serial.println("VERY GOOD");
}
else if(dustVal2<301)
{
Serial.println("GOOD");
}
else if(dustVal2<1051)
{
Serial.println("FAIR");
}
else if(dustVal2<3001)
{
Serial.println("POOR");
}
else
{
Serial.println("VERY POOR");
}


if(dustVal>118)
//此拟合公式有效y=0.172*x-0.0999
{
float dustVal3=dustVal;
dustVal3=((dustVal3*5/1024)*0.172-0.0999)*1000;
Serial.println("PM2.5:");
Serial.println(dustVal3);//实际的颗粒数
}
else
{
Serial.println("PM2.5:");
Serial.println("----");
}



}

我修改的程序

1. 
   
2. #include <Wire.h>
   
3. #include <TM1650.h>
   
4. char s[10];
   
5. float dustVal3;
   
6. int dustPin=A0;
   
7. int dustVal=0;
   
8. 
   
9. int ledPower=2;
   
10. int delayTime=280;
    
11. int delayTime2=40;
    
12. float offTime=9680;
    
13. void setup(){
    
14. Serial.begin(9600);
    
15. pinMode(ledPower,OUTPUT);
    
16. //pinMode(4, OUTPUT);
    
17. }
    
18. 
    
19. void loop(){
    
20. // ledPower is any digital pin on the arduino connected to Pin 3 on the sensor
    
21. digitalWrite(ledPower,LOW); // power on the LED
    
22. delayMicroseconds(delayTime);
    
23. dustVal=analogRead(dustPin); // read the dust value via pin 5 on the sensor
    
24. delayMicroseconds(delayTime2);
    
25. digitalWrite(ledPower,HIGH); // turn the LED off
    
26. delayMicroseconds(offTime);
    
27. 
    
28. delay(3000);
    
29. Serial.println(dustVal);
    
30. 
    
31. 
    
32. float dustVal2=dustVal;
    
33. dustVal2=(dustVal2*5/1024-0.0356)*120000;
    
34. Serial.println(dustVal2);//实际的颗粒数
    
35. 
    
36. if(dustVal2<76)
    
37. {
    
38. Serial.println("EXCELLENT");
    
39. }
    
40. else if(dustVal2<151)
    
41. {
    
42. Serial.println("VERY GOOD");
    
43. }
    
44. else if(dustVal2<301)
    
45. {
    
46. Serial.println("GOOD");
    
47. }
    
48. else if(dustVal2<1051)
    
49. {
    
50. Serial.println("FAIR");
    
51. }
    
52. else if(dustVal2<3001)
    
53. {
    
54. Serial.println("POOR");
    
55. }
    
56. else
    
57. {
    
58. Serial.println("VERY POOR");
    
59. }
    
60. 
    
61. 
    
62. if(dustVal>118)
    
63. //此拟合公式有效y=0.172*x-0.0999
    
64. {
    
65. dustVal3=((dustVal3*5/1024)*0.172-0.0999)*1000;
    
66. Serial.println("PM2.5:");
    
67. String dataString;
    
68. dataString=dtostrf(dustVal3,3.0,s);
    
69. TM1650 displayString(dataString);//实际的颗粒数
    
70. }
    
71. else
    
72. {
    
73. Serial.println("PM2.5:");
    
74. Serial.println("----");
    
75. }
    
76. 
    
77. 
    
78. 
    
79. }
    
80. 
    
81. 
    

复制代码

liuxue4503

有个更好用的：sprintf
char *displayString=new char[10];
float data=333.3333;
sprintf( displayString, "%f", data );

mondaywoo

初学者学习