Add lines (data) to a fopen file without overwriting the previous data

Hi, I would like to know please how to add data to an fopen file without overwrting the previous data I am using NS = fopen([‘Valu_Var’ num2str(realiz)’.txt’],’w+’);

Answer 1

[Stephen23]

Try the append option:

https://www.mathworks.com/help/matlab/ref/fopen.html#btrnibn-1-permission

NS = fopen(... ,'a+');
%                ^ try this

[Eliane Youssef]

Hi, thank you it works.

[Eliane Youssef]

I have another issue that seems to exist. I have a matrix where I am also saving my values and when adding the new lines (lines: y+(tt/0.2)+1), it replaces the old lines (lines: y) by zeros and writes the new lines afterwards.

I am using:

for realiz = 1:...

NS = fopen(['Valu_Var' num2str(realiz) '.txt'],'a+');

for y = 1:...

y;

Var_NS(y+(tt/0.2)+1,realiz)= EvalRandomField(...);

fprintf(NS,'Var(');

fprintf(NS,'%d',y+(tt/0.2)+1); ...

fprintf(NS,'%f\n',Var_NS(y+(tt/0.2)+1,realiz));

end

fclose(NS);

end

save('Var_NS','Var_NS','-v7.3')