Function string_to_table is breaking on 3rd if c - c

Question

I am trying to create program to add two matrixes. After typing input like [12 4] program crashes when function strcat starts.
I have no idea what is wrong. func.h consists of stdio.h, _mingw.h,stdlib.h and string.h
#include"func.h"
void string_to_table(double **matrix, char inpt[])/*problematic function*/
{
printf("convertion start");
int i=strlen(inpt);
printf("%i",i);
int j=1;
int k=0,l=0;
char num[128];
double converted=0;
printf("breakpoint1");
while(j<(i-1))
{
if(inpt[j]==' ')
{
printf("first if");
converted=atof(num);
num[0]='\0';
matrix[k][l]=converted;
++l;
printf("breakpoint2");
}
else if(inpt[j]==';')
{
printf("second if");
converted=atof(num);
num[0]='\0';
matrix[k][l]=converted;
++k;
l=0;
}
else
{
printf("third if");
strcat(num,inpt[j]);/*place when everything crashes*/
}
++j;
}
printf("convert0 end");
}
void add_matrix(double **matrix1, double **matrix2,int i,int j)
{
int k=0;
int l=0;
while(k<i)
{
while(l<j)
{
matrix1[k][l]+=matrix2[k][l];
++l;
}
l=0;
++k;
}
int matrixproccesing(int *i,int *j, char m[])/*sprawdzanie poprawnosci wejscia*/
{
printf("macro start");
int columnnum=0,rownum=0,x=0,piv=0,check=0;
int textsize=strlen(m);
printf("%i",i);
printf("loop start");
printf("%i",textsize);
while(x<(textsize-1))
{
printf("%i",x);
printf("\n");
if(x==0)/*czy poczatek to [*/
{
if(m[x]!='[')
return 0;
}
else if(x==(textsize-2))/*czy koniec to]*/
{
printf("kohec");
if(m[x]==']')
break;
return 0;
}
else if((m[x]>47&&m[x]<58)||(m[x]==' ')||(m[x]=='.')||(m[x]==';')||(m[x]=='-'))/*czy liczba*/
{
if(m[x]==';')/*czy ilosc liczb w rzedzie taka sama*/
{
if(check==0)
{
check=columnnum;
}
else if(check!=columnnum)
{
return 0;
}
printf("colnum");
columnnum=0;
rownum++;
}
else if(m[x]==' ')/*czy nowa liczba/kolumna */
{
columnnum++;
}
}
++x;
}
*i=(check+1);
*j=(columnnum+1);
printf("macro end");
return 1;
}
int is_same_size(int a, int b,int c ,int d)/*test rozmiaru*/
{
if((a==c)&(b==d))
return 1;
return 0;
}
void print_da_matrix(double **matrix, int i, int j)
{
int k=0,l=0;
printf("[ ");
while(k<i)
{
while(l<j)
{
printf("%f",matrix[k][l]);
printf(" ");
}
printf(";");
l=0;
if(k<(i-1))
++k;
}
printf("]");
}
void release_the_memory(double **matrix, int i)
{
int k=0;
while(k<i)
{
free(matrix[k]);
++k;
}
free(matrix);
matrix=NULL;
}
}
int main()
{
int i=0,j=0,m1=0,m2=0,tabcr=0;
char matrix[512];
fgets(&matrix,511,stdin);
double **matrix1;
double **matrix2;
if(!matrixproccesing(&i,&j,matrix))
{
printf("zle wejscie");
return 0;
}
matrix1=(double**)malloc(i*sizeof(double *));
while(tabcr<j)
{
matrix1[tabcr]=(double*)malloc(j*sizeof(double));
++tabcr;
}
string_to_table(matrix1,matrix);
printf("\n");
printf("podaj druga macierz");
fgets(&matrix,511,stdin);
if(!matrixproccesing(&m1,&m2,matrix))
{
printf("zle wejscie");
return 0;
}
tabcr=0;
if(!is_same_size(i,j,m1,m2))
{
printf("matrixes have different size.");
return 0;
}
matrix2=(double**)malloc(i*sizeof(double *));
while(tabcr<j)
{
matrix2[tabcr]=(double*)malloc(j*sizeof(double));
++tabcr;
}
string_to_table(matrix2,matrix);
add_matrix(matrix1,matrix2,i,j);
/* print_da_matrix(matrix1,i,j);
release_the_memory(matrix1,i);
release_the_memory(matrix2,i);*/
return 0;
}