assembly - Mips dynamic memory allocation and pointers -

i building compiler bison , encountered problem. need dynamically allocate memory , store string print content.

i thought saving pointer in data section allocating memory save address in pointer, assign string val print it. problem when trying print string prints first char. here code example.

.data      p: .word 0 # pointer save allocated memory first address. .text      li $v0,9    #allocate instruction     li $a0,64   # allocate 64 byte     syscall     sw $v0,p    #save first memory address pointer p      li $t0,'a'  #write first byte 'a' cahr     sw $t0,0($v0)     li $t0,'b'  #write first byte 'a' cahr     sw $t0,4($v0)      li $v0,4    #print instruction     lw $a0,p     syscall 

this result in char on mars console. ideas why?

i'm guessing: chars stored in bytes. b should go in 1($v0) not 4($v0) , you'll need null in 2 terminate.