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sscanf optional column
sscanf(currentline[i], "%[^t] %[^t] %11 [^n]", aIDVar, someDataVar, furtherDatVar) ==  3

#include <stdio.h>

static void testFn (char *str) {
    int var1, var2, var3;

    if (sscanf(str, "%d %d %d", &var1, &var2, &var3) !=  3) {
        var3 = 42;
        if (sscanf(str, "%d %d", &var1, &var2) !=  2) {
            var1 = var2 = var3 = -1;
        }
    }
    printf ("[%-10s] -> %3d %3d %3dn", str, var1, var2, var3);
}

int main (void) {
    testFn ("");
    testFn ("1");
    testFn ("1 2");
    testFn ("1 2 3");
    testFn ("1 2 3 4");

    return 0;
}

[          ] ->  -1  -1  -1
[1         ] ->  -1  -1  -1
[1 2       ] ->   1   2  42
[1 2 3     ] ->   1   2   3
[1 2 3 4   ] ->   1   2   3

static void testFn (char *str) {
    int quant, var1, var2, var3;

    if ((quant = sscanf(str, "%d %d %d", &var1, &var2, &var3)) !=  3)
        if (quant ==  2)
            var3 = 42;
        else
            var1 = var2 = var3 = -1;
    printf ("[%-10s] -> %3d %3d %3dn", str, var1, var2, var3);
}

void input(char *str){
    int x, vars[3];
    char *sp;
    for(x=0,sp=strtok(str, " t");x<3&&sp; x++,sp=strtok(NULL, " t")){
          vars[x] = atoi(sp);
    }
    if(x<3) //didn't read enough
       //..deal with it
    if(sp) //your optional field is present
       //deal with that.
}