How can I know whether my RNG implementation can be considered cryptographically secure or not?

I wrote this RNG in C. It creates a random Output of ASCII characters in the range between 33 - 122. An Output of 100 characters for example, looks like the following:

Q:[X-Nl&G'1aqvAk<k^@ir@,ZcUIrWT6n0f"fRv+GEsO[r>DFUC)si<3F?an>qS2+Do+j.?R;+3,;yVu.@jpDE9haA

Here is the full Code which compiles flawlessly with gcc on Windows:

#include <stdio.h>
#include <ctype.h>
#include <time.h>
#include <stdlib.h>

int checkIfNum(char *c);
int checkIfAlNum(char *c);

int main(int argc, char * argv[]){
    clock_t time1 = clock();
    FILE * write;
    int i = 0;
    int length;
    int status;
    unsigned int j = 0;
    if((argc < 2) || argc > 3){
        printf("USAGE: keygen FILENAME LENGTH(MAX: 200.000.000)\nPRESS ANY KEY TO EXIT...\n");
        getchar();
        return -1;
    }
    status = checkIfAlNum(argv[1]);
    if(status == -1){
        printf("ERROR: INVALID FILENAME. USE ONLY ALPHANUM CHARACTERS\n");
        return -1;
    }
    status = checkIfNum(argv[2]);
    if(status == -1){
        printf("ERROR: INVALID KEYLENGTH. MAX: 200.000.000\n");
        return -1;
    }

    length = atoi(argv[2]);

    srand(time(NULL));
    write = fopen(argv[1], "w+");
    if(write == NULL){
        printf("ERROR: COULD NOT CREATE FILE.\n");
    }

    while(i < length){
        time1 = clock();
        j = ((rand()+time1)%(122-33)+33);
        i++;
        fputc(j, write);
    }

    fclose(write);
    return 0;
}

int checkIfNum(char *c){
    int i = 0;
    while(c[i] != '\0'){
        if((isdigit(c[i]) == 0) && i > 9){
            return -1;
        }
        i++;
    }
    return 0;
}

int checkIfAlNum(char *c){
    int i = 0;
    while((c[i]) != '\0'){
        if((isalnum(c[i]) == 0) && i > 30){
            return -1;
        }
        i++;
    }
    return 0;
}

Can my implementation be considered cryptographically secure?

I will be very grateful for constructive Feedback