string operations

[bookimal]

Hi,

i want to write a function with prototype

void makeString(char *arrayOfStrings[])

and in it, I want it to make a string beginning with a number x, x is a global variable in my code, followed by all of arrayOfStrings, seperated by spaces.

So eg..
x = 5, arrayOfStrings[0] = "hello", arrayOfStrings[1] = "how", arrayOfStrings[2] = "are", arrayOfString[3] = "you?"

and I want makeString to create:
char * s = "5 hello how are you?"

How would I go about doing that.. first of all I don't know how to convert an integer into a string, apart from when I do printf....

Please help me..

Thanks~!

[MacGyver]

Not that hard overall.... Logic is roughly as follows:

1. Allocate enough memory to hold the entire new string.
2. Put number and space into the string via sprintf() or snprintf().
3. Start a loop for each element in the array of strings.
4. For each string, call strcat() and append the string to the new string, and then add a space.

Hence.... in your example, you'd need 21 bytes to fit "5 hello how are you?". Then you'd first put the number into the new string. Then concatenate each word onto the new string. First it would be "5 ", and then "5 hello ", etc.

You have to take care not to print an extra space at the end, though.

[anon]

It's probably not going to work with this prototype. You'll need to pass all necessary data and get the result back somehow. So may-be something more like this:

char* makeString(int value, char *arrayOfStrings[], int sizeOfArray)

You might need these functions: sprintf for numeric conversion and strcat for appending. You'll also need to make sure you create (or provide) a char array that is large enough to hold the concatenated string.

First it would be "5 ", and then "5 hello ", etc.

You have to take care not to print an extra space at the end, though.

That problem would be solved by starting with "5", then appending: "5 ", "5 hello" etc.

[bookimal]

This is what I've came up with so far:

void makeString(char *args[]) {
  int j;
  char tmpBuffer[MAX_LINE+3];
  char *tmpBufferPointer = &tmpBuffer[0];
  sprintf(tmpBufferPointer,"%d: ",numOfCommands);
  for (j = 0; j < MAX_LINE/2+1; j++) {
    if (args[j] == NULL) break;
    strcat(tmpBufferPointer, args[j]);
    strcat(tmpBufferPointer, " ");  
  }
}

(MAX_LINE/2 + 1 is the size of args)

I think this will add a space right after the last non null element of args.. but I'm not sure how I can avoid that, since I don't know when args[j] will become null.

Also, is there another way to loop through args without using a for loop? I haven't programmed in C for about 2 years and I remember there used to be some standard method to go through arrays, somehow use pointers? If anyone can jolt my memory that would be great!

Thanks