char* 转 string

const char *name = "hello";
String Str = name;

Serial.printf("%s\n", Str);

string 转 char*

String str = "hello";
char *p = (char *)str.c_str();

Serial.printf("%s\n", p);

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 char *转 char[]

const char *str = "hello";
char str1[10];

strncpy(str1, str, strlen(str) + 1); // 注意加1操作
Serial.printf("%s\n", str1);

char[] 转 char *

char str[] = "hello";
char *p = str;

Serial.printf("%s\n", p);

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char[] 转 string

char st[] = "hello";
String str = st;

Serial.printf("%s\n", str);

string 转 char[]

String str = "My test";
char ch[] = "hello";

strncpy(ch, str.c_str(), str.length() + 1); // 注意加1
Serial.printf("%s\n", ch);

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 int 转 char *

int a = 10;
char str[10];

sprintf(str, "%d", a);
Serial.printf("%s\n", str);