What is wrong with my square root code? - c

Question

What is wrong with this code? I am learning both Python and C at the same time. Similar code on Python works fine but I am confused why this does not work here?
#include <stdio.h>
float a, b, c,min_value, max_value;
int main(){
printf("Enter a number here:");
scanf("%f",&a);
b=(max_value+min_value)/2;
while(abs(b*b-a)>0.1){
if (b*b>a){
max_value=b;
b=(max_value+min_value)/2;
}
else if(b*b<a){
min_value=a;
b=(max_value+min_value)/2;
}
printf("the square root of the number is %f",b);
}
}

Answer 1

In C, abs is an integer function - passing float values to it will result in truncation, so small values < +/-1.0 will just become 0. You need to use fabs for floating point values. Change:
while(abs(b*b-a)>0.1){
to:
while(fabs(b*b-a)>0.1){
and add:
#include <math.h>
near the top of your source file.

Answer 2

A lot of things are wrong:
float a, b, c,min_value, max_value;
You shouldn't declare these variables outside the main function.
b=(max_value+min_value)/2;
max_value and min_value are not defined, what are you expecting here?
if (b*b>a){
max_value=b;
b=(max_value+min_value)/2;
}
else if(b*b<a){
min_value=a;
b=(max_value+min_value)/2;
}
Once again, max_value and min_value may not be defined. I could continue.
If you are trying to implement a sqrt function, perhaps you should take a look at someone else's code, as it seems obvious you lack knowledge in C.

Answer 3

For future references, please state what your program is trying to accomplish and what errors are occuring. Not trying to be mean or condescending; just giving you a heads up on Stack Overflow policy on question phrasing.
That said, on a brief glance I did notice that you also did not define "max_value" or "min_value" before using them in line 6 (where you set a value to "b"). In addition, declaring your variables outside the main function makes them global variables, which I would suggest avoiding if your variables are not going to be used in another program (via "#include ").