目錄

• 效果
• • 普通數字
  • 小數
  • 科學記數法
• 源碼

平臺：
STC89C52
Keil uVision V5.29.0.0
PK51 Prof.Developers Kit Version:9.60.0.0

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效果

這里以51單片機為例，對串口接收的字符串中的第三個數進行解碼：

普通數字

小數

科學記數法

源碼

/* * Str2Num.h * * Created on: 2021/11/6 * Author: 乙酸氧鈹 */#ifndef STR2NUM_H_ #define STR2NUM_H_#include "stdint.h"/* str:數字字符串首地址 flag:分隔符 no:第no個數字 從1開始計 Output: 輸出結果 */extern void str2int(char * str, char flag, int32_t no, int32_t *Output); extern void str2double(char * str, char flag, int32_t no, double *Output);#endif /* STR2NUM_H_ */ /* * Str2Num.c * * Created on: 2021/11/6 * Author: 乙酸氧鈹 */ #include "Str2Num.h"void str2int(char * str, char flag, int32_t no, int32_t *Output) {int32_t id_end, count, output;for (id_end = 0, count = 0; count != no; ++id_end){if (str[id_end] == flag || str[id_end] == '\r' || str[id_end] == '\n' || str[id_end] == '\0')++count;}id_end -= 2;for (output = 0, count = 1; str[id_end] != flag && id_end >= 0; --id_end){ if (str[id_end] == '-')output *= -1;else if (str[id_end] == '+');else {output += (str[id_end] - '0') * count;count *= 10;}}*Output = output; }void str2double(char * str, char flag, int32_t no, double *Output) {int32_t id_end, id_dot, id_e, count, id, pow;double output;for (id_end = 0, count = 0; count != no; ++id_end){if (str[id_end] == flag || str[id_end] == '\r' || str[id_end] == '\n' || str[id_end] == '\0')++count;}id_end -= 2; //尋找最后一個數字的下標for (id_dot = id_end, id_e = -1; str[id_dot] != '.'; --id_dot){if (str[id_dot] == 'e' || str[id_dot] == 'E')id_e = id_dot; //標記e的下標if (str[id_dot] == flag || str[id_dot] == '\r' || str[id_dot] == '\n' || str[id_dot] == '\0'){if(id_e > 0)id_dot = id_e;elseid_dot = id_end + 1; break;}}output = 0;if (str[id_dot] == '.'){for (count = 10, id = id_dot + 1; str[id] != flag && str[id] != '\r' && str[id] != '\n' && str[id] != '\0' && str[id] != 'e' && str[id] != 'E'; ++id){output += (str[id] - '0') / (double)count; //加入小數部分count *= 10;}}for (count = 1, id = id_dot - 1; str[id] != flag && id >= 0; --id){if (str[id] == '-')output *= -1;else if (str[id] == '+');else{output += (str[id] - '0') * count;count *= 10; //加入整數部分}}if(id_e > 0) //指數計算{ for (pow = 0, count = 1; id_end != id_e; --id_end){if (str[id_end] == '+');else if (str[id_end] == '-')pow *= -1;else { pow += (str[id_end] - '0') * count;count *= 10;}}if (pow > 0)while (pow--)output *= 10;else if(pow < 0)while (pow++)output /= 10;}*Output = output; }

總結

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