C ++ unsigned int进行双重转换

Question

What is the right way of converting unsigned int to double ? I need this is for QCPCustomPlot for data setting, as it takes in QVector<double> precisely as parameter for creating a graph.

EDIT: Silly me. The 'memory leak' error issue was caused because I initialised QVector<double> x(time), y(ipv4int) wrongly. Changed the time value to the same as ipv4int (the data occurence frequency) and the x and y matched correctly.

Done with the time variable, now the actual issue regarding the conversion. How can I convert it to double format that holds value such as 1855919686 instead of in the format of 1.85592e+09 ?

QCustomPlot requires double but it seems that the QVector<double> couldn't take in value like 1.85592e+09

Updated code:

QVector<double> x(i), y(totalIP); //i=236052
for(int o = 0; o <= i; o++){
    double dSec = arrayIPxTime[o][0] - startSecond; //arrayIPTime[o][0] holds time in second
    double dMin = dSec/60;
    double ipv4addr = arrayIPxTime[o][1]; //arrayIPTime[o][0] holds ipaddr in integer format
    x[o] = dMin;
    //y[o] = ipv4addr; this is the line that causes crash. 
    qDebug()<<"Count "<<o<<" time "<< x[o] <<" ipv4 "<<ipv4addr<<" arrayIPxTime[o][1] "<<arrayIPxTime[o][1];
}

Current output:

Count  236048  time  62.3167  ipv4  1.85592e+09  arrayIPxTime[o][1]  1855919686
Count  236049  time  62.3167  ipv4  1.85592e+09  arrayIPxTime[o][1]  1855919686
Count  236050  time  62.3167  ipv4  1.85592e+09  arrayIPxTime[o][1]  1855919686
Count  236051  time  62.3167  ipv4  1.85592e+09  arrayIPxTime[o][1]  1855919686

Answer 1

Rest assured that converting an unsigned int to a double does not cause a memory leak.

Writing double b = a; is more than sufficient, or just pass a into the function that requires a double as a parameter.

Note that the conversion is exact for an unsigned int up to the 53rd power of 2, for an IEEE754 double precision floating point type.

Answer 2

What's the value of time ? It looks like you do:

QVector<double> x(time);
// [...]
x[o] = dMin;

If time == 166, no doubt x[166] is going to fail, since the vector is initialized with a size of time !

And by the way, nothing related to casting to double .