以逗号分隔的字符串的解析函数

假设我有一个像这样的字符串"cmd,param1,param2" 。 String是Arduino String类型。 https://www.arduino.cc/en/Reference/String

我想提取用逗号分隔的每个子字符串。 我已经成功编写了像这样的特定案例的代码。 这是代码;

 String = str_data('cmd,param1,param2'); int firstCommaIndex = str_data.indexOf(','); int secondCommaIndex = str_data.indexOf(',', firstCommaIndex+1); String cmd = str_data.substring(0, firstCommaIndex); String param1 = str_data.substring(firstCommaIndex+1, secondCommaIndex); String param2 = str_data.substring(secondCommaIndex+1); 

我的问题是有一个解决一般情况的函数。 该字符串可以用任意数量的逗号分隔。 我想有一个看起来像这样的function;

 String parserCommaDelimited(String input_delimited_str, int nth_param_num) { //implementation } 

假设input_delimited_str="cmd,param1,param2,param3,param4"

parserCommaDelimited(input_delimited_str, 1)返回"cmd" 。 parserCommaDelimited(input_delimited_str, 5)返回"param4" 。

Answer 1

以下是基本的CSV解析器：

 void readCSVline(char *line); char *readCSVfield(char *line, char *buf); void readCSVdemo(void) { char line[]= "0,,10004,10004,\"Albany Hwy After Galliers Av\",\"\",-32.13649428,116.0176090070,3"; readCSVline(line); } /* readCSVline is where you put your "intelligence" about fields to read * and what to do with them */ void readCSVline(char *line) { char field1[80], *lineptr=line; int nfields=0; while (*lineptr) { lineptr= readCSVfield(lineptr, field1); printf("%s\n", field1); nfields++; } printf("%d fields read.\n", nfields); } /* readCSVfield reads a field from a CSV line until the next comma or end-of-line. * It returns where the reading stopped. */ char *readCSVfield(char *line, char *buf) { int instr= FALSE; // track whether we are in a string char *cptr= line; while (*cptr) { if (instr) { if (*cptr=='"') { char cc= *++cptr; if (cc=='"') // escaped double quote *buf++ = '"'; else { *buf='\0'; cptr--; instr= FALSE; } } else *buf++ = *cptr; } else switch (*cptr) { case '"': instr= TRUE; break; case ',': cptr++; *buf= '\0'; return(cptr); case ' ': case '\t': case '\n': case '\r': break; default: *buf++ = *cptr; } cptr++; } *buf= '\0'; return(cptr); } 

Answer 2

您可以按如下方式拆分字符串并获得您想要的任何内容

 int split(char *result[], const char *str, char tok) { char buff[1024]; // it's better to use length of str instead of 1024 int idx = 0; int len = 0; int ent_cnt = 0; int st = 0; // parse string while(1) { char ch = str[len++]; // need checking len to avoid overflow // end of string? if (ch == '\0') break; switch(st) { case 0: { if (ch == tok) st++; else buff[idx++] = ch; break; } case 1: { if (idx) { char *entry = malloc(idx + 1); int i; for (i = 0; i < idx; i++) entry[i] = buff[i]; entry[i] = '\0'; result[ent_cnt++] = entry; idx = 0; } // normal char? if (ch != tok) buff[idx++] = ch; st--; break; } default: break; } } // process last part if any if (idx) { char *entry = malloc(idx + 1); int i = 0; for (i = 0; i < idx; i++) entry[i] = buff[i]; entry[i] = '\0'; result[ent_cnt++] = entry; } return ent_cnt; } int main(int argc, char *argv[]) { char *result[10]; int cnt = split(result, "s,this,is,a,test,", ','); int i = 0; for (i = 0; i < cnt; i++) { printf("%s\n", result[i]); } if (cnt != 5) { printf("Fail!\n"); } return 0; } 

Answer 3

尝试使用split，在c ++中是strtok：

variable = strtok（variable，“delimiter”）; 把字符串转换成数组，用c ++我不知道，我用php和javascript编程，但是你可以看到：

http://www.cplusplus.com/reference/cstring/strtok/

我希望它对你有所帮助！