String management How to manage Scilab's String read and write process using call_scilab and api_scilab

## Description

This help describes how strings and matrix of strings can be handle through the Call Scilab API and api Scilab.

There are several functions which can be used to read / write from the memory of Scilab. These functions are described in dedicated pages.

Note: Access to variables is done through api Scilab (named variable).

## Examples

    // This example shows how to write a Scilab string in Scilab engine
    // It is the equivalent to A="my Message"; in Scilab interpreter
    // See: modules/call_scilab/examples/basicExamples/readwritestring.c

    // StartScilab
    int row = 1, col = 1; /* Size of the matrix */
    /* Declare the string */
    char **myMatrixOfString = (char**)malloc(sizeof(char*) * row * col);
    myMatrixOfString[0]="my Message";
    char variableName[] = "A";
    SciErr sciErr;

    /* Write it into Scilab's memory */
    sciErr = createNamedMatrixOfString(pvApiCtx, variableName, row, col, myMatrixOfString);
    if(sciErr.iErr)
    {
    	printError(&sciErr, 0);
    }

    /*
     * Prior to Scilab 5.2
     * C2F(cwritechain)(variableName, &sizeOfMyString  , myString, strlen(variableName), sizeOfMyString);
    */

    printf("Display from Scilab of A:\n");
    SendScilabJob("disp(A);"); /* Display A */

    /* Load the previously set variable A */
    // See: modules/call_scilab/examples/basicExamples/readwritestring.c

    char variableToBeRetrieved[]="A";
    int iRows       = 0;
    int iCols       = 0;
    int i,j;
    int* piAddr     = NULL;
    int* piLen      = NULL;
    char** pstData  = NULL;
    SciErr sciErr;

    //first call to retrieve dimensions
    sciErr = readNamedMatrixOfString(pvApiCtx,variableToBeRetrieved,&iRows, &iCols, NULL, NULL);
    if(sciErr.iErr)
    {
    	printError(&sciErr, 0);
    }

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

    printf("\n");
    printf("Load and display of A:\n");
    for(j = 0 ; j < iCols ; j++)
    {
    	for(i = 0 ; i < iRows ; i++)
    	{
    		/* Display the formatted matrix with same scilab index */
    		printf("[%d,%d] = %s\n",j+1,i+1,pstData[j* iRows + i]);
    	}
    }

    printf("\n");
    free(piLen);
    for(i = 0 ; i < iRows * iCols ; i++)
    	{
    		free(pstData[i]);
    	}
    free(pstData);

## See also

- Call_Scilab
- api Scilab
- SendScilabJob
- StartScilab
- Call_Scilab: Boolean Management
- Call_Scilab: Double Management
- Complex Management