C - create a string "from" struct parameter -

have

typedef struct person {     char name[20]     char surname[20] } person_t; 

i need create string xxxxxx:yyyyyy function char* persontostring(person_t *p). tried make it:

char* persontostring(person_t* p) {    int n1,n2;   n1=strlen(p->name);   n2=strlen(p->surname);   char *p = (char*) malloc((n1+n2+2)*sizeof(char));   strcat(p,puser->name);   strcat(p,":");   strcat(p,puser->surname);    return p; } 

this give me reasonable output have errors testing valgrind! think there way more classy write function!

when malloc memory p memory hold garbage values. strcat append string after null character, in uninitialized string hold random values.

replace first strcat strcpy.