Double precision data type conversion in c language

hello friend,

Explanation:The program does not rely on any function provided by the system.

My code is as follows:

#include
#define ARR_MAX 10

bool IsDig(const char c){
char Cdig[12]={"0123456789."};
for (int i=0;i<11;i++)
{
if(Cdig[i]==c) return true;
}
return false;
}
int str_len(const char *t){
int len=0;
for(;*t!='\0';t++) ++len;
return len;
}
void Initial(double *r){
for(int i=0;i*r=0.0;
}
}
void main(void)
{
char test[100]={"afadfe545.568adf48dfeea89.51fvae10648.789"};
bool find_mark=false;
double acceptD,temp,accept_dec,E_integer,E_decimal,result[ARR_MAX];
int i,k,k2,m,mark_index,digLen,lens,index;
acceptD=temp=accept_dec=E_integer=E_decimal=0.0;
digLen=index=i=0;
lens=str_len(test);
Initial(&result[0]);

for (i=0;i{
if(IsDig(test[i])) ++digLen;
else{
if(digLen>0){

acceptD=test[i-1]-48; // Get single digits.
k=1;
while(k {
E_integer=1;
for(m=1;m<=k;m++) E_integer*=10; // Index Multiplier(Such as: 10,100,1000 and so on...)
temp=test[i-1-k]-48;
acceptD=acceptD+temp*E_integer;
++k;
if(test[i-1-k]=='.') // If there is a decimal point.
{
mark_index=k;
accept_dec=acceptD;
acceptD=0.0;

E_decimal=1;
for(m=1;m<=mark_index;m++)
E_decimal*=0.1;
accept_dec*=E_decimal; // Convert to decimal.
find_mark=true;
}
if(find_mark)
{
++k;
acceptD=test[i-1-k]-48;
++k;
k2=1;
while (k {
E_integer=1;
for(m=1;m<=k2;m++) E_integer*=10;
temp=test[i-1-k]-48;
acceptD+=(temp*E_integer);
++k;
++k2;
}
}

}
digLen=0; // Reset for zero.
if(find_mark){
acceptD+=accept_dec;
result[index++]=acceptD;
find_mark=false; // Reset for false.
}
else result[index++]=acceptD;
}
}
}

// Prevent tail figures:

if(digLen>0){

acceptD=test[i-1]-48;
k=1;
while(k{
E_integer=1;
for(m=1;m<=k;m++) E_integer*=10;
temp=test[i-1-k]-48;
acceptD=acceptD+temp*E_integer;
++k;
if(test[i-1-k]=='.')
{
mark_index=k;
accept_dec=acceptD;
acceptD=0.0;

E_decimal=1;
for(m=1;m<=mark_index;m++)
E_decimal*=0.1;
accept_dec*=E_decimal;
find_mark=true;
}
if(find_mark)
{
++k;
acceptD=test[i-1-k]-48;
++k;
k2=1;
while (k{

E_integer=1;
for(m=1;m<=k2;m++) E_integer*=10;
temp=test[i-1-k]-48;
acceptD+=(temp*E_integer);
++k;
++k2;
}
}

}
digLen=0; // Reset for zero
if(find_mark){
acceptD+=accept_dec;
result[index++]=acceptD;
find_mark=false; // Reset for false.
}
else result[index++]=acceptD;
}

// Print the get result.
for(i=0;i}

// It printed result is:
545.5680004.2
48.0000004.2
89.5100004.2
10648.7890004.2

//In fact, I want results should look like this:

545.568
48.0
89.51
10648.789

How to do it?

Thank for you.

2 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes12y ago
Accepted answer
So you want output to 3 decimal places but you want to suppress insignificant trailing zeros.

This is impossible using the normal printf specifiers but you can do it by using sprintf to print the number to a string buffer and then get rid of the trailing zeros manually.

Check out this SO thread for some code:

http://stackoverflow.com/questions/277772/avoid-trailing-zeroes-in-printf
Ken H12y ago
Thank for you. :)