Declare dynamic length array

[Devjaz]

Hello,

I have the following declaration:

char name[name_size + 1] = {'\0'}; sprintf(name, "Auto_%s_Workflow", typeName);

So I have a variable 'typeName' and a variable 'name'. The varaibale 'name' stores a string of characters in the following format: Auto_'typeName'_Workflow. The length of 'typeName' is determined at run time and I want to know how to declare the variable 'name' which will hold a name with dynamic lenth in C.

Thank you

[VictorN]

Is your code the C one or C++?
If C++ - then use std::string rather than plain char array.

[2kaud]

For c, consider

	int sz = 0;
	char *buf = NULL;
	char typeName[] = "qwertry";

	sz = snprintf(buf, sz, "Auto_%s_Workflow", typeName) + 1;
	buf = malloc(sz);
	snprintf(buf, sz, "Auto_%s_Workflow", typeName);

	printf("%s\n", buf);

	free(buf);

This will allocate the required memory to buf to hold the requested string and the null delimiter and will then put the string into buf. The trick here is to call snprintf() twice. The first call doesn't actually write any data as sz is 0 but returns the number of bytes required to be allocated to hold the string (less the terminating null). Then snprintf() is called again with the allocated memory pointer and the correct size so the data is written to buf.