How to sscanf with negative float?-CodePudding

Actually I have a string with this type:

"1,Hello,E025FFDA,-126.56,52.34,true"

And I want to parse it using sscanf to store those value in variable of corresponding type so

uint, char[], maybe string here, ufloat ?, float, bool

I use sscanf with "%[^',']" format specifier and I test each value if it is correct or not and in a certain range.

Here is my code:

param is the pointer to the beginning of the string
temp2 a temporary variable
local_ptr is a copy of param to not modify param
RCV a struct with all my parameters

if((get_param_length(param) != 0) && (sscanf(local_ptr, "%[^',']", &temp2) == 1))
    RCV.binarypayload = temp2;
else
    error = 1;

Do you have any idea of the best type to store my values? Or maybe any advice?

CodePudding user response：

There is no type that could match your ufloat. All floating point types are signed so extracting from your string could be done like this:

#include <math.h>     // if you want to use fabsf()
#include <stdbool.h>
#include <stdio.h>
#include <string.h>

int main() {
    unsigned u1, u2;
    char str1[20], boolstr[6];
    float f1, f2;
    const char *local_ptr = "1,Hello,E025FFDA,-126.56,52.34,true";
    bool b;

    if(sscanf(local_ptr, 
       " %u,[^,],%X,%f,%f,%5s", &u1, str1, &u2, &f1, &f2, boolstr) == 6)
    {
        b = strcmp(boolstr, "true") == 0;
        printf("%u %s %X %f %f %d\n", u1, str1, u2, f1, f2, b);
    }
}

Possible output:

1 Hello E025FFDA -126.559998 52.340000 1

If you want to get the absolute value from f1, just add f1 = fabsf(f1); after the sscanf.

CodePudding user response：

Assuming "1,Hello,E025FFDA,-126.56,52.34,true" is the string you want to parse, you can do it like this:

#include <stdio.h>

int main()
{
    char string[] = "1,Hello,E025FFDA,-126.56,52.34,true";

    unsigned int i;
    char s1[10]; // You can adjust the size here and update it in sscanf()
    char s2[10];
    float f1, f2;
    char s3[10];
    
    if (sscanf(string, "%u,%9[^,],%9[^,],%f,%f,%9s", &i, s1, s2, &f1, &f2, s3) != 6)
        printf("Error parsing\n");
    else
        printf("%u, %s, %s, %f, %f, %s", i, s1, s2, f1, f2, s3);
}

This will output:

1, Hello, E025FFDA, -126.559998, 52.340000, true

If you want to store "true" in a bool:

bool b = !strcmp(s3, "true"); // else false