scanf: floating point format not linked

Question

I'm getting error scanf: floating point format not linked while reading value for 'info'of following structure.

struct node
{
    float info; struct node *next;
}*start;

in main()

void main()
{
       struct node *temp;
       temp = (struct node*)malloc(sizeof(struct node));
       printf("enter data = ");
       scanf("%f",&temp->info);
}

its not reading any value for that scanf and coming out of program.

How to get around this ?

Solution 1

This issue is most likely seen when using Turbo C/ Borland C compilers. These compilers do not link in the floating-point (f-p) library unless we need it. Therefore, by force we need to add any floating-point (f-p) function when we have "%f" or other floating point (f-p) formats in scanf() or printf() calls.

To fix this error, call a floating-point (f-p) function or just add link of a file, which contains at least one floating-point (f-p) function. eg.

void dummy(float *a) {
    float b=*a; //perform some floating access
    dummy (&b); //calling a floating point function
}

Solution 2

Solution 1:

According to the following link: http://docs.embarcadero.com/products/rad_studio/radstudio2007/RS2007_helpupdates/HUpdate4/EN/html/devwin32/rte_printf_scanf_float_not_linked_xml.html

you can add following code to one source module (and it worked for me):

extern _floatconvert;
#pragma extref _floatconvert

Example:

#include<....>
.............

extern _floatconvert;
#pragma extref _floatconvert

int main(){......}
..........
..........

---

Solution 2:

Add the following dummy function in source code:

void dummy()
{
    float f,*fp;
    fp=&f;
}

Solution 3

Floating-point formats contain formatting information that is used to manipulate floating-point numbers in certain runtime library functions, such as scanf() and atof(). Typically, you should avoid linking the floating-point formats (which take up about 1K) unless they are required by your application. However, you must explicitly link the floating-point formats for programs that manipulate fields in a limited and specific way.

Refer to the following list of potential causes (listed from most common to least common) to determine how to resolve this error:

CAUSE: Floating point set to None. You set the floating-point option to None when it should be set to either Fast or Normal.

FIX: Set Floating Point to Fast or Normal.

CAUSE: Either the compiler is over-optimizing or the floating-point formats really do need to be linked. You need the floating-point formats if your program manipulates floats in a limited and specific way. Under certain conditions, the compiler will ignore floating-point usage in scanf(). For example, this may occur when trying to read data into a float variable that is part of an array contained in a structure.

FIX: Add the following code to one source module:

SOLUTION: Just add the following function in your program. It will force the compiler to include required libraries for handling floating point linkages.

static void force_fpf() /* A dummy function */
{

       float x, *y; /* Just declares two variables */
       y = &x;      /* Forces linkage of FP formats */
       x = *y;      /* Suppress warning message about x */
}