How to convert double to const char*

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C

double x = 0.123f;
char s[50] = {0};
sprintf(s, "%lf",x);

but how to spintf "XPosition"+"0.123" ?

What I have tried:

sprintf(s, "%lf","XPositon"+x);

Posted 11-Jan-19 15:20pm

xuyunhai20160827

Updated 11-Jan-19 17:04pm

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2 solutions

Solution 2

Did you try something like:

C++

sprintf(s, "XPositon%lf", x);

Just like with printf.

Posted 11-Jan-19 17:04pm

Patrice T

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k5054 · Accepted Answer · 2019-01-11T16:56:00

sprintf works just like printf, but outputs to a string, rather than stdout so

C++

printf("Xposition %lf", x);

becomes

C++

sprintf(s, "Xpostion %lf", x);

sprintf can produce buffer overflows, so better to use snprintf(), instead. e.g.

C++

snprintf(s, 50, "Xposition %lf", x)

. More generally the signature for snprintf is

int snprintf(char *str, size_t size, const char *format, ...);

Note that snprintf() truncates output if it would exceed the designated size, but returns the number of chars it would have written if enough space was available this means you can

C++

if( snprintf(s, 50, "Xpostion %lf" x) > 50) {
    // handle buffer overflow ...
}