C language float variable and string conversion occupy memory size problem

dinghao1

C language float variable and string conversion occupy memory size problem [Copy link]

 

1. Without string conversion, the program size is 48B

1. #include<reg52.h>
2. #include<stdio.h>
3. #define uchar unsigned char float fengsu; long guang; uchar str[10]; void display1() { guang=60000; // sprintf(str,"%5ld",guang); } void display2() { fengsu=12.34; // sprintf(str,"%5.2f",fengsu); } void main() { while(1) { display1(); display2(); } }

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dinghao1

2. Add string conversion, program size 2594B

1. #include<reg52.h>
2. #include<stdio.h>
3. #define uchar unsigned char float fengsu; long guang; uchar str[10]; void display1() { guang=60000; sprintf(str,"%5ld",guang); } void display2() { fengsu=12.34; sprintf( str,"%5.2f",fengsu); } void main() { while(1) { display1(); display2(); } }

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dinghao1

3. Float variables are not converted, and the program size is 2559B

1. #include<reg52.h>
2. #include<stdio.h>
3. #define uchar unsigned char float fengsu; long guang; uchar str[10]; void display1() { guang=60000; sprintf(str,"%5ld",guang); } void display2() { fengsu=12.34; // sprintf(str,"%5.2f",fengsu); } void main() { while(1) { display1(); display2(); } }

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dinghao1

4. Delete the float variable and only convert long integers. The program size is 1110B #include
#include
#define uchar unsigned char float fengsu; long guang; uchar str[10]; void display1() { guang=60000; sprintf(str,"%5ld",guang); } void display2() { //fengsu=12.34; //sprintf(str,"%5.2f",fengsu); } void main() { while(1) { display1(); display2(); } }

dinghao1

Why does code size vary so much?

freebsder

Of course the code size will be larger if there are more sprintfs. This function itself is not small. Floating point is adapted through software on U without hardware floating point. You can't see it but the compiler does it for you behind the scenes.

dinghao1

freebsder published on 2018-7-26 14:44 Of course the code size will be larger if there are more sprintfs. This function itself is not small. Floating point is adapted through software on U without hardware floating point. You see...

Is there a smaller function suitable for converting variable numbers into characters and then displaying them through the 12864 LCD screen? Below It is a display program english(2,4,5,str) which displays the 5 characters of str starting from the fourth character of the second line

1. write(0,0x01); english(2,1,15,table3) ;//Lighting guang=6000; guang=guang*10; sprintf(str,"%5ld",guang); english(2,4,5,str);

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huo_hu

The floating point arithmetic library is not included if you are not using floating point numbers, so this is normal.

freebsder

dinghao1 published on 2018-7-26 16:32 Is there a smaller function suitable for converting variable numbers into characters and then displaying them on the 12864 LCD screen? The following is a display program english (...

Write one yourself. Baidu, there should be some few.

freebsder

dinghao1 published on 2018-7-26 16:32 Is there a smaller function suitable for converting variable numbers into characters and then displaying them on the 12864 LCD screen? The following is a display program english (...

Write one yourself. Baidu, there should be some few.

dinghao1

huo_hu published on 2018-7-26 17:15 The floating point arithmetic library is not included if you are not using floating point numbers, so it is normal to be small.

Is there a smaller function suitable for converting variable numbers into characters and then displaying them through the 12864 LCD screen? I originally displayed it one by one, and there was a lot of real-time data to be displayed. The program was too big, 51 I can’t take up more space, so I’ll add a string conversion function, and then the string display program will be smaller.

1. write(0,0x01); english(2,1,15,table3);//illumination guang=1234; write( 0,0x93); write(1,0x30+guang/10000); write(1,0x30+guang/1000%10); write(0,0x94); write(1,0x30+guang/100%10); write (1,0x30+guang/10%10); write(0,0x95); write(1,0x30+guang%10);

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dinghao1

freebsder published on 2018-7-26 17:57 Write one yourself. If you search on Baidu, there should be quite a few.

Someone on Baidu said that using the sprintf function, the result was 2k larger than the original,

freebsder

dinghao1 published on 2018-7-26 16:32 Is there a smaller function suitable for converting variable numbers into characters and then displaying them on the 12864 LCD screen? The following is a display program english (...

Write one yourself. Baidu, there should be some few.

huo_hu

The display part is made into a function, which can be called without floating point. The number of decimal places in the integer is specified.