NRF_LOG_INFO can't print a string.

Question

Hello, 
 The following code was embedded in main function, the sdk version is 15.2. 
 
 
NRF_LOG_INFO("test begin: ");

char string[] = "This is a string.";
NRF_LOG_INFO(string);

NRF_LOG_INFO("This is a string, too.");

NRF_LOG_INFO("test end ");

 
 the debug console show as below:

My question is , why string "This is a string" can't print out? 
 
 Thank you!

Henry_Chou · Accepted Answer

static const char string[]="This is a string."; is okay. 
 Or you may declare the string[] for global memory. 
 In your case,the char* string will effect in local function. The memory is temporary. 
 NRF_LOG_INFO((uint32_t) string); 
 Henry

Susheel Nuguru · Answer

The reason is because NRF_LOG_XXX uses many macro definitions that assumes that the args of the NRF_LOG are similar to printf. It uses __VA_ARGS__ and hence what you are trying to do does not make sense to the macro expansion of the NRF_LOG_INFO. 
 To achieve what you want you should use a format indicator as below. 
 NRF_LOG_INFO("test begin: ");

static char string[] = "This is a string.";
NRF_LOG_INFO("%s", string);

NRF_LOG_INFO("This is a string, too.");

NRF_LOG_INFO("test end"); 
 You will get what you need then

NRF_LOG_INFO can't print a string.

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