I have a char array with the following:
And I need to convert them to an integer array that should end up like this:Code:char initCost[] = {"0", "-1", "0"};
I have tried many different approaches that I found online but no luck yet. Any help will be greatly appreciated.Code:int initCost[] = {0, -1, 0};
One approach is to use the ASCII approach where you take the character itself and subtract it based on its value.
'0' is 48 so 48 - 48 is 0.
'1' is 49 so 49 - 48 is 1.
You can also use atoi the function to convert each character to an integer but the problem with this is that it does not protect you against overflow and underflow.(Now that I recall I think atoi uses the ASCII approach as well)
My personal recommendation is to strtol as it tells you if you got an overflow or underflow and helps you when you are doing validation. The only thing is that you are going to have truncate to an int because it converts a string to a long.
Last edited by deathslice; 04-11-2016 at 12:38 PM.
stdlib.h has a function called "atoi". This will take a string and return the int value.
C library function - atoi()
Code:int get_random_number(void) { return 4; //chosen by fair dice roll. //guaranteed to be random }
If you want to convert strings to integers, look into functions like "strtol".
However, this is not right:
You are trying to initialize an array of char with strings. You could use characters (e.g. '0' instead of "0"), but this would make representing -1 more difficult. Perhaps you meant to use an array of char*.Code:char initCost[] = {"0", "-1", "0"};
I see what you mean, but the situation here is that I am reading into my char buffer[256] data that looks like this:
0, -1, 0, 1, 0, 1, 2, 1, 3, 3, 2, 7
So I need to be able to convert that into individual integers and stotr them into a int array. I apologize for the confusion, I am brand new to these site.
I see what you mean, but the situation here is that I am reading into my char buffer[256] data that looks like this:
0, -1, 0, 1, 0, 1, 2, 1, 3, 3, 2, 7
So I need to be able to convert that into individual integers and stotr them into a int array. I apologize for the confusion, I am brand new to these site.
Where are you reading this data from? Does the data conform to a specific format?
Its coming from another pc, this is part of a client/server communication program.
bzero(buffer, 256);
n = read(clntsocket, buffer, 255);
Well, I mean, char is just a smaller int:
The cast isn't even required.Code:int main(void) { size_t x = 0; char buffer[256] = {0, -1, 0, 1, 0, 1, 2, 1, 3, 3, 2, 7}; int content[256] = { 0 }; for (x = 0; x < 12; x++) { content[x] = (int) buffer[x]; printf("content[%2zu] = %d\n", x, content[x]); } printf("...\n"); return 0; } content[ 0] = 0 content[ 1] = -1 content[ 2] = 0 content[ 3] = 1 content[ 4] = 0 content[ 5] = 1 content[ 6] = 2 content[ 7] = 1 content[ 8] = 3 content[ 9] = 3 content[10] = 2 content[11] = 7 ...
I had done that but I get this back:
array[0] = 48
array[1] = 44
array[2] = 50
array[3] = 44
array[4] = 49
array[5] = 44
array[6] = 49
array[7] = 44
array[8] = 45
array[9] = 49
array[10] = 44
array[11] = 48
Okay, well, we could have gotten here faster than how we did. It's always good to post a short, simple, self-contained, correct example. Anytime you go onto a programming forum (not just these) it is helpful to post one to understand the problem, and find a solution, faster.
The reason this was hard for you was because you have some commas and hyphens in the data you read.
array[1] = 44 = ','
...
array[8] = 45 = '-'
...
You need a parsing strategy that can deal with this cruft. The good thing is we know the buffer is zero terminated. Note the call to bzero(), and reading a slightly smaller string in the code fragment you gave us, graciously, in post #8.
That means you can do something similar to this:
The code does assume that array is large enough for all the data. If that could be untrue, then you would have to check x against array's size in order to avoid an out of bounds array write.Code:#include <stdlib.h> char *p = buffer; char *trail; size_t x = 0; while (*p != '\0') { array[x] = strtol(p, &trail, 10); if (*trail == ',') { p = trail + 1; ++x; } else if (*trail == '\n' || *trail == '\0') { break; } else { fprintf(stderr, "parsing error: expected ',' got: '%c'\n", *trail); break; } }
Last edited by whiteflags; 04-11-2016 at 07:47 PM.
You can also use sscanf.
Code:#include <stdio.h> #define ASIZE 100 int main() { char buf[] = "0, -1, 0, 1, 0, 1, 2, 1, 3, 3, 2, 7"; int a[ASIZE]; int d = 0, n = 0, sz = 0, i; char *b; for (b = buf; sscanf(b, "%d ,%n", &d, &n) == 1; b += n) { if (sz >= ASIZE) { fprintf(stderr, "Error: array overflow\n"); break; // print them anyway } a[sz++] = d; } for (i = 0; i < sz; i++) printf("%2d: %2d\n", i, a[i]); return 0; }
You have a comma-separated list of numbers (44 is the ASCII decimal value for comma).
Some additional ideas, beyond what has been suggested:
Look into using "strtok" to break up the string into separate number sub-strings, and convert each sub-string to its equivalent number.
Use "strtol" directly, though you'd have to be careful with the pointers to take the commas into account:
Code:#include <stdio.h> #include <stdlib.h> int main(void) { char str[] = "0,-1,0,1,0,1,2,1,3,3,2,7"; char *p; int data[12]; int i; data[0] = strtol(str, &p, 10); for(i = 1; i < 12; i++) data[i] = strtol(p+1, &p, 10); for(i = 0; i < 12; i++) printf("%d\n", data[i]); return 0; }
Last edited by Matticus; 04-11-2016 at 08:00 PM.
I want to thank you all for your great help, I was able to make it work!!!! Thank you again
