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Scilab manual >> API Scilab > Low level functions > String reading (Scilab gateway)

String reading (Scilab gateway)

How to read matrices of strings in a gateway.

Calling Sequence

Input argument profile:

SciErr getMatrixOfString(void* _pvCtx, int* _piAddress, int* _piRows, int* _piCols, int* _piLength, char** _pstStrings)
SciErr getMatrixOfWideString(void* _pvCtx, int* _piAddress, int* _piRows, int* _piCols, int* _piLength, wchar_t** _pwstStrings)

Named variable profile:

SciErr createNamedMatrixOfString(void* _pvCtx, const char* _pstName, int _iRows, int _iCols, char** _pstStrings)
SciErr createNamedMatrixOfWideString(void* _pvCtx, const char* _pstName, int _iRows, int _iCols, wchar_t** _pwstStrings)

Arguments

_pvCtx

Scilab environment pointer, pass in "pvApiCtx" provided by api_scilab.h.

_piAddress

Address of the Scilab variable.

_pstName

Name of the variable for "named" functions.

_piRows

Return number of rows.

_piCols

Return number of columns.

_piLength

Address of array of strings length (must be allocated size: _piRows * _piCols)

_pstStrings

Address of array of char* (must be allocated size: _piRows * _piCols)

_pwstStrings

Address of array of wchar_t* (must be allocated size: _piRows * _piCols)

SciErr

Error structure where is stored errors messages history and first error number.

Description

This help describes how matrix of strings can be handled through the Scilab API.

Gateway Source

int read_string(char *fname,unsigned long fname_len)
{
    SciErr sciErr;
    int i,j;
    int iLen        = 0;
    //variable info
    int iRows        = 0;
    int iCols        = 0;
    int* piAddr        = NULL;
    int* piLen        = NULL;
    char** pstData    = NULL;

    //output variable
    int iRowsOut    = 1;
    int iColsOut    = 1;
    char* pstOut    = NULL;

    //check input and output arguments
    CheckRhs(1,1);
    CheckLhs(1,1);

    //get variable address
    sciErr = getVarAddressFromPosition(pvApiCtx, 1, &piAddr);
    if(sciErr.iErr)
    {
        printError(&sciErr, 0);
        return 0;
    }

    //fisrt call to retrieve dimensions
    sciErr = getMatrixOfString(pvApiCtx, piAddr, &iRows, &iCols, NULL, NULL);
    if(sciErr.iErr)
    {
        printError(&sciErr, 0);
        return 0;
    }

    piLen = (int*)malloc(sizeof(int) * iRows * iCols);
    //second call to retrieve length of each string
    sciErr = getMatrixOfString(pvApiCtx, piAddr, &iRows, &iCols, piLen, NULL);
    if(sciErr.iErr)
    {
        printError(&sciErr, 0);
        return 0;
    }

    pstData = (char**)malloc(sizeof(char*) * iRows * iCols);
    for(i = 0 ; i < iRows * iCols ; i++)
    {
        pstData[i] = (char*)malloc(sizeof(char) * (piLen[i] + 1));//+ 1 for null termination
    }
    //third call to retrieve data
    sciErr = getMatrixOfString(pvApiCtx, piAddr, &iRows, &iCols, piLen, pstData);
    if(sciErr.iErr)
    {
        printError(&sciErr, 0);
        return 0;
    }

    //computer length of all strings
    for(i = 0 ; i < iRows * iCols ; i++)
    {
        iLen += piLen[i];
    }

    //alloc output variable
    pstOut = (char*)malloc(sizeof(char) * (iLen + iRows * iCols));
    //initialize string to 0x00
    memset(pstOut, 0x00, sizeof(char) * (iLen + iRows * iCols));

    //concat input strings in output string
    for(i = 0 ; i < iRows ; i++)
    {
        for(j = 0 ; j < iCols ; j++)
        {
            int iCurLen = strlen(pstOut);
            if(iCurLen)
            {
                strcat(pstOut, " ");
            }
            strcpy(pstOut + strlen(pstOut), pstData[j * iRows + i]);
        }
    }

    //create new variable
    sciErr = createMatrixOfString(pvApiCtx, Rhs + 1, iRowsOut, iColsOut, &pstOut);
    if(sciErr.iErr)
    {
        printError(&sciErr, 0);
        return 0;
    }

    //free memory
    free(piLen);
    for(i = 0 ; i < iRows * iCols ; i++)
    {
        free(pstData[i]);
    }
    free(pstData);
    free(pstOut);

    LhsVar(1) = Rhs + 1;
    return 0;
}

Scilab test script

a_ref = ["may the puffin be with you"];
a = ["may", "the", "puffin"; "be","with","you"];
b = read_string(a);
if a_ref <> b then error("failed"), end
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with contributors 		Last updated:
Wed Jan 26 16:25:14 CET 2011