CODEWITHSUNDEEP
cchar
forever_fighting_21
forever_fighting_21

Reputation: 101

Adding char* variables together?

Very simple question but within my code I have two char* variables. 

char* port = "1100";
char* ip = inet_ntoa(((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr);

The first is a port number and the second tells the ip address of a given interface.

If I wanted to create a new variable say, char* both, why is it that I cannot say: 

char* both = ip + port;

with the output of 172.21.8.179 1100? How can I get a new variable with that output? Thanks

Upvotes: 0

Views: 2848

Answers (3)

Beyondo
Beyondo

Reputation: 3247

You can use sprintf() function call

...

sprintf(char * buffer, const char * format, ...)

Dynamic

char* res = (char*)malloc(15);
char* str1 = "Hello ";
char* str2 = "World!";
sprintf(res, "%s%s", str1, str2);
puts(res); // Hello World!

Static

char res[15];
char str1[] = "Hello ";
char str2[] = "World!";
sprintf(res, "%s%s", str1, str2);
puts(res); // Hello World!

you're able to add integers into a C string too with the %d format specifier.

Upvotes: 0

pm100
pm100

Reputation: 50120

you probably want to use snprintf

char buff[100];
snprintf(buff, sizeof(buff), "%s %s", port, ip);

Upvotes: 1

Jashaszun
Jashaszun

Reputation: 9270

You can't add two strings in C because, well, they're not actually strings. They're just pointers. And adding two pointers results in a pointer that points at the address that is the sum of the two original addresses.

To concatenate two char*s together, you can use the strcat(char * destination, const char * source) function. Just make sure that your both pointer is pointing to enough memory to actually hold the concatenated string!

Upvotes: 0

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