sprintf does not give the expected result

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I have variables of the type Unsigned Long Int and would like to save its value in a string, to perform calculation of checksum and send via serial communication. void Payload(int long unsigned lastTime, float deltaOne, float deltaTwo, int factor){

[...]
sprintf(buffer, "CAPTION,%u,%s,%s,%d," lastTime,deltaOne,deltaTwo,factor);
SendWithCS(buffer);
}

But the converted value of int for string it’s not the same. Example: 

int long unsigned record = 11285600;
float delta1 = 50.2035;
float delta2 = 54.2035
int factor = 5;
Payload(record,delta1,delta2,factor);

Exit:

CAPTION,22601,50.2035,54.2035,5,3F
c c++ string variables int

  • Why is the first a pointer? Will you send this value or pointer? How can 5 data get out if you are only using 4? This code does not even compile, it has many errors.

  • ops, I typed wrong rs

  • There are other errors, see all. Read the whole comment above.

  • This code is part of another much larger code, but as the other parts are not relevancy just put a fragment of it, the last output value is given by the Sendwithcs; 54.2035,5,

  • Why should you show 22601 if what you’re going through is 11285600?

  • That’s the question, why are you showing 22601 if I’m passing 11285600?

  • Your question is confused, because this seemed to be what you expected. Actually I used your code, there is a lot of error in it, and it does not generate that no, certainly the code you are running is different from this posted.

  • This code will not compile, it depends on other functions, it is only possible to explain the part of sprintf , the only doubt is why I enter the variable in the function and the buffer string is presented with a value that differs from the original format.

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1 answer

1

The code has several errors, after tidying them up what was left was the wrong formatting. View existing options.

This is a C code compiled with C++. These functions are avoided in idiomatic code C++.

The no-signal number was wrong, and the floating-point ones too.

#include <iostream>
using namespace std;

void Payload(unsigned long lastTime, float deltaOne, float deltaTwo, int factor) {
    char buffer[sizeof(unsigned long) + sizeof(float) + sizeof(float) + sizeof(int) + 13];
    sprintf(buffer, "CAPTION,%u,%.4f,%.4f,%d,", lastTime, deltaOne, deltaTwo, factor);
    printf("%s", buffer);
    printf("\nCAPTION,11285600,50.2035,54.2035,5,\n");
}

int main() {
    unsigned long record = 11285600UL;
    float delta1 = 50.2035;
    float delta2 = 54.2035;
    int factor = 5;
    Payload(record, delta1, delta2, factor);
}

Behold working in the ideone. And in the repl it.. Also put on the Github for future reference.

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